Many 3D printed parts aren’t 100% ready straight out of the printer, which is where additive post-processing comes in. Post-processing techniques like sanding and smoothing can improve the look and feel of your part, but other post-processing techniques such as the application of metal inserts, enhance its mechanical properties or geometric accuracy. In some cases, post-processing inserts may need to be added to ensure that a part functions as intended, meets its design specifications, and is ready for customer use.

Additive post-processing inserts serve different purposes, including allowing for printed parts to be fastened to other components, eliminating the need for rivets or adhesives, and helping to streamline the manufacturing process. Since metal is more durable than plastic, certain inserts can even increase part durability, meaning that 3D printed plastic products can be repeatedly assembled and disassembled without damage.

Three are three general types of additive post-processing inserts available: press-fit inserts, heat-staked inserts, and Helicoil inserts. Each insert type is better suited to different 3D printing processes and use-cases: with that in mind, we’re here to help you understand which is the right fit for your project.

Additive Post-Processing Inserts

Press-Fit Inserts

Press-fit is the most common additive post-processing insert type, and is best suited to Carbon Digital Light Synthesis (DLS), HP Multi Jet Fusion (MJF), and stereolithography (SLA) parts. While tapping a part or integrating threads into its design may be an option for 3D-printing projects, plastic threads will wear or break down relatively quickly compared to metal press-fit insert threads. With that issue in mind, press-fit inserts are often used in cases that require high load-carrying capabilities and durability, such as 3D-printed plastic housings, casings, consumer electronics, and other parts that need to accept screws for assembly.

To use a press-fit insert, you’ll need to design your part with a hole, or drill one after the print is complete. Adding the insert will be relatively easy once you have your hole: press-fit inserts are tapered, so they will self-align as they are pressed in. Instead of tapping the hole or melting the plastic before installing an insert into a 3D-printed part, you can simply use a hammer or arbor press to set it into place. Since press-fit inserts often have knurled outer surfaces, they will stay in place once inserted.

Heat Staked Inserts

It’s also possible to use heat-staked inserts with additive parts. Best suited for MJF and FDM printing projects, heat staking involves heating the insert to melt the plastic, and pushing it into place as it cools. Raising and cooling the temperature of 3D plastic components will enable the material to re-form around the insert, creating a strong bond with the printed part. You’ll need to pay attention to how much heat and pressure you apply when installing heat-staked inserts in order to achieve the best results. 

Heat staking not only reduces a part’s complexity by eliminating the need for CAD thread design or rivets, but increases its durability and improves cosmetic appearance. Threaded inserts that have been heat-staked (rather than 3D printed or tapped) will also have greater pull-out strength and be able to better resist stripping, pull-out loads, and torque-out loads. As a result, using heat staking to fix metal inserts and fasteners into 3D printed parts is a common practice in many industries, including the automotive, telecom, and appliance industries, and the process is used on everything from electronic enclosures to appliance dials.

Helicoil Inserts

Helicoil inserts are traditionally used in metal parts but can also be used in FDM 3D prints, regardless of whether a part has a 3D printed thread or a traditionally drilled and tapped hole. Also known as helical inserts and screw thread inserts (STI), Helicoil inserts are coiled wire inserts with coils that are wider than the hole into which they are inserted. To install a Helicoil insert, you’ll need to drill and tap, or 3D print, a threaded hole, before screwing the insert onto an installation tool and installing it. The coil will then expand, forming a tight seal against the existing threads.

There are several types of Helicoil inserts available. Stanley Engineering, for example, offers HeliCoil threaded wire inserts that provide internal threads for standard-sized fasteners and screw locking wire inserts that offer permanent conventional screw threads. Stanley Engineering also produces free-running wire inserts with threads that can be used from both ends, and tangless threaded inserts that are wear-resistant and eliminate the need for tang retrieval.

Metal Helicoil inserts are strong, durable, and resistant to heat. They also prevent threaded holes from wearing out, and so can lengthen a 3D printed part’s lifespan. Helicoil inserts are commonly used in the aerospace, defense, automotive, medical, and telecom industries.

Creating Strong, Durable Parts With SyBridge

Press-fit inserts, heat-staked inserts, and Helicoil inserts offer everything from increased part durability to the possibility of a more streamlined manufacturing process. However, since each insert type is best suited to different project requirements, incorrect installation can damage plastic parts and end up increasing production times and costs. Given the importance of inserts to certain projects, and their associated challenges, it makes sense to work with an experienced manufacturer like SyBridge to ensure that you select the right insert for your needs. 

When you work with SyBridge, you won’t need to be a manufacturing expert to add inserts to your 3D-printed parts, or to navigate any aspect of production. Our team of experts will guide you through the manufacturing process, helping you refine your designs to ensure that your parts are optimized for quality and cost at every stage, and meet your expectations on completion. It’s easy to get your project started: simply create an account and upload your design, and we’ll generate an instant quote for your parts. Prior to generating a quote, you’ll be able to adjust part materials and manufacturing methods, and run automated design for manufacturing (DFM) checks to identify issues with your part. To learn more about post-processing inserts, or any of our manufacturing services, contact us today. 

The post Your Guide to Additive Post-Processing Inserts appeared first on SyBridge Technologies.

All post-processing increases part costs and production timelines, but the right surface finish has the potential to bring your design vision to life. Metal finishing for CNC machined parts typically encompasses a variety of mechanical processes, such as tumbling, brushing, and bead blasting, but metal parts may also be treated with chemical finishes such as passivation and zinc plating.

Amongst many useful results, chemical finishing can remove blemishes from a part, alter its conductivity levels, extend its lifespan, and even increase its resistance to wear and corrosion. Chemical finishes have an array of industrial applications: in the aerospace industry, for example, companies use chemical finishes to increase parts’ durability, improve thermal stability, and slow oxidation. In the consumer goods industry, chemical finishes can be found in the production of everything from enclosures and casings to sporting equipment.

While there are plenty of chemical finishes available, they aren’t necessarily interchangeable between materials. In fact, every chemical finish is typically compatible with specific materials and offers its own advantages and disadvantages. In this guide, we’ll explore several common chemical finishing processes so that you can decide which will work best for your CNC manufacturing project.

Choosing Your Chemical Finish

When choosing a chemical finish for your part, you’ll need to think about both compatible materials and end use. This means considering an array of contextual factors, including: 

• The environment your part will be used in
• Whether it requires conductive or insulating properties
• How much weight it will need to bear
• How much wear it will need to withstand
• Tolerance requirements
• Color and transparency requirements
• Surface finish standards
• Any other relevant or desired properties.

To help you evaluate your options, here are some common chemical finishes and their compatible materials:

Let’s take a closer look at these chemical processes, how they work, and how they might benefit your project. 

Anodizing

A popular aluminum finishing option, anodizing thickens the natural oxide layer on part surfaces, creating an anodic oxide film that confers increased protection and improved aesthetics. In the case of aluminum, to form the anodized protective layer, you’ll need to bathe your part in an acid electrolyte bath and then apply a cathode (a negatively charged electrode) to cause the solution to release hydrogen. At the same time, the aluminum part (the positively charged anode) will release oxygen, forming a protective oxide layer on its surface. After a part has been anodized, its surface will have microscopic pores which must be sealed with a chemical solution to prevent corrosion and any build up of contaminants. 

Anodized parts are durable and resistant to corrosion and abrasion, which can reduce maintenance costs down the line. The anodized layer is electrically non-conductive and is fully integrated with the aluminum substrate, so it won’t chip or flake away like plating and paint often do. In fact, in addition to sealing, the porous anodized layer can be painted or dyed, and since anodized finishes are non-toxic and chemically stable, they’re also more environmentally friendly. Anodizing isn’t just a finish for aluminum: the process is also possible for titanium and other non-ferrous metal parts. 

There are three different types of anodization:

• Type I (chromic acid anodizing) results in the thinnest oxide layer, which means it won’t change your part’s dimensions. Type I anodized elements will appear grayer in color and won’t absorb other colors well.
• Type II (boric-sulfuric acid anodizing) has better paint adhesion and is slightly thicker than Type I. With Type II anodizing, you can easily create anodized parts that are blue, red, gold, black, or green.
• Type III (hard sulfuric acid anodizing) is the most common form of anodizing. It has the clearest finish, which means it can be used with more colors. It’s worth noting that Type III anodizing results in a slightly thicker finish than Type II anodizing.

The increased durability, abrasion resistance, and corrosion resistance of anodized parts, and the high level of dimensional control that the process offers, makes anodizing particularly popular in aerospace and construction. Beyond those industries, anodized metal components are found in a wide variety of applications including curtain walls, escalators, laptops, and more.

Despite its broad applications, there are drawbacks to anodization:

• Anodizing metal will change the dimensions of your part, so you’ll need to consider the oxide layer when determining dimensional tolerances or use chemical or physical masks to ensure specific areas of your part remain untreated.
• It can be challenging to achieve a true color match if your anodized components aren’t treated in the same batch. Color fading may also occur.
• Anodizing a metal part will increase its electrical and thermal resistance. In some cases, this might be the intention, but in others, you may need to use a mask to ensure your part retains its full conductivity in certain sections.
• Anodizing will increase your part’s surface hardness.

Passivation

This popular metal finishing process prevents corrosion in stainless steel parts, helping them retain their cleanliness, performance, and appearance. Not only will passivated parts be far more resistant to rust, and thus better suited to use outdoors, they’ll also be less likely to pit, last longer, be more aesthetically pleasing, and more functional. Accordingly, passivation is used across a variety of industries, from the medical industry where sterilization and longevity are key, to the aerospace industry where businesses seek high steel quality and tight dimensional tolerances.

Passivation involves the application of nitric or citric acid to a part. While nitric acid has traditionally been the typical choice for passivation, citric acid has recently increased in popularity because it can produce shorter cycle times, and is safer and more environmentally friendly. During the passivation process, parts are submerged in an acid-based bath to remove any iron and rust from their surfaces without disturbing the chromium. The application of acid to stainless steel removes any free iron or iron compounds from its surface, leaving behind a layer composed of chromium (and sometimes nickel). After exposure to the air, these materials react with oxygen to form a protective oxide layer. 

It’s important to bear in mind that passivation can extend part production time. Before a part can be passivated, it must be cleaned to remove any greases, dirt, or other contaminants, and then rinsed and soaked (or sprayed). While submersion is the most common passivation method because it offers uniform coverage and can be completed quickly, an acidic spray may be used as an alternative. 

Black Oxide Coating

A finish for ferrous metals like steel, stainless steel, and copper, the black oxide coating process involves immersing parts in an oxide bath to form a layer of magnetite (Fe₃O₄), which offers mild corrosion resistance.

There are three types of black oxide coating:

• Hot black oxide: The hot black oxide coating process involves dipping a part into a hot bath of sodium hydroxide, nitrites, and nitrates in order to turn its surface into magnetite. After bathing, parts will need to be submerged in alkaline cleaner, water, and caustic soda, and then coated with oil or wax to achieve the desired aesthetic.
• Mid-temperature black oxide: Mid-temperature black oxide coating is very similar to hot black oxide coating. The main difference is that coated parts will blacken at a lower temperature (90 – 120 °C). Since this is below the boiling point of the sodium and nitrate solution, there’s less need to worry about caustic fumes.
• Cold black oxide: While hot and mid-temperature black oxide coating involves oxide conversion, cold black oxide relies on deposited copper selenium to alter a part. Cold black oxide is easier to apply but rubs off more quickly and provides less abrasion resistance.

Parts that have received black oxide coating will have greater corrosion and rust resistance, be less reflective, and will have much longer life cycles. The oil or wax coating will add water resistance and may also make your parts easier to clean by preventing harmful substances from reaching the metal interior. Black oxide coating will also add thickness, making it ideal for drills, screwdrivers, and other tools that require sharp edges that won’t dull over time.

Chem Film

Chem film, also known as chromate conversion coating, or by its brand name Alodine®, is a thin coating typically used on aluminum (although it can be applied to other metals) to prevent corrosion and improve adherence of adhesives and paints. Chem film finishes often have proprietary formulas, but chromium is the main component in every variety. A chem film finish can be applied via spraying, dipping, or brushing, and, depending on product and formula, may be yellow, tan, gold, or clear in color.

While other finishes reduce thermal and electrical conductivity, chem film finishing allows aluminum to maintain its conductive properties. Chem film is also relatively cheap and, as noted, provides a good base for painting and priming (for additional time-saving benefits). Since it’s prone to scratches, abrasion, and other superficial damage, however, chem film isn’t ideal for projects in which aesthetic appearance is a top priority.

Electropolishing

Electropolishing is an electrochemical finishing process commonly used to remove a thin layer of material from steel, stainless steel, and similar alloys. During the electropolishing process, a part is submerged in a chemical bath and an electric current is applied to dissolve its surface layer. Various parameters affect the part’s finish, including the chemical composition of the electrolyte solution, its temperature, and the part’s exposure time.

Electropolishing generally removes between 0.0002 and 0.0003 inches from an object’s surface, leaving smooth, shiny, and clean material behind. Other benefits of electropolishing include improved corrosion resistance, increased part longevity, improved fatigue strength, a lower coefficient of friction, reduced surface roughness, and the elimination of surface defects such as burrs and micro-cracks.

Electropolishing is compatible with steel, stainless steel, copper, titanium, aluminum, brass, bronze, beryllium, and more. It’s worth noting that electropolishing is faster and cheaper than manual polishing, though it still takes time and won’t remove 100% of rough surface defects. 

Electroplating

Electroplating is effectively the reverse of electropolishing. Instead of removing a layer of metal to achieve a finished surface, electroplating deposits an additional outer layer, increasing a part’s thickness. Compatible with cadmium, chrome, copper, gold, nickel, silver, and tin, electroplating creates smooth parts that experience less wear and tear over time thanks to their additional protection from corrosion, tarnishing, shock, and heat. Electroplating can increase adhesion between the base material and its additional outer coating, and, depending on the type of metal used, can make your part magnetic or conductive.

In contrast to other CNC machining finishes, electroplating isn’t particularly eco-friendly since it creates hazardous waste that can seriously pollute the environment if disposed of improperly. Electroplating is also relatively costly, as a result of the metals and chemicals (and other necessary materials and equipment) that it requires, and can be time-consuming, especially if a part requires multiple layers.

Chrome Plating

Chrome plating, or chromium plating, is a type of electroplating that involves adding a thin layer of chromium to a metal part to increase its surface hardness or resistance to corrosion. The addition of a chrome layer can make cleaning a part easier and improve its aesthetics, and nearly all metal parts can be chrome plated, including aluminum, stainless steel, and titanium.

The chrome plating process generally involves the degreasing, manual cleaning, and pretreatment of a part before it is placed in a chrome plating vat. The part must then stay in the vat long enough for the chrome layer to reach a desired thickness. Since the process consumes electricity, and involves multiple steps, chrome plating is a relatively expensive finishing process.

Polytetrafluoroethylene (Teflon™) Coating

Polytetrafluoroethylene (PTFE) coating, commonly known as Teflon™, is available in powder and liquid forms, and is used across the industrial landscape. Some PTFE applications only require one coat, but others need both a primer and a topcoat to ensure maximum protection. The finish can be applied to a range of metals including steel, aluminum, and magnesium.

PTFE-coated parts have non-stick surfaces, a low coefficient of friction, and are highly resistant to abrasions. Since PTFE coating has low porosity and surface energy, coated parts will be resistant to water, oil, and chemicals. PTFE can also withstand temperatures up to 500°F, can be easily cleaned, and offers great electrical insulation and chemical resistance.

Due to its chemical resistance and non-stick properties, PTFE is often used to coat fuel pipes and to insulate circuit boards in computers, microwaves, smartphones, and air conditioners. It is also commonly used to coat medical tools and equipment, and cookware. Although it is popular across industries, the PTFE coating process is relatively expensive and isn’t as long-lasting as other chemical finishing options.

Electroless Nickel Plating

Electroless nickel plating refers to the addition of a protective layer of nickel-alloy to metal parts. In contrast to the electroplating process, which involves an electric current, electroless nickel plating involves the use of a nickel bath and a chemical reducing agent like sodium hypophosphite to deposit a layer of nickel-alloy (often nickel-phosphorus) onto parts. The nickel-alloy deposits uniformly, even on complex parts with holes and slots. 

Parts finished with nickel plating have increased resistance to corrosion from oxygen, carbon dioxide, salt water, and hydrogen sulfide. Nickel-plated parts also have good hardness and wear resistance and, with additional heat treatment, can become even harder. Electroless nickel plating is compatible with a variety of metals, including aluminum, steel, and stainless steel. 

Electroless nickel playing has its challenges. Common problems include the build up of contaminants in nickel baths, rising phosphorus content, and subsequent reductions in plating rates. Additionally, the wrong temperature or pH level can create coating quality issues like pitting, dullness, and roughness. Electroless nickel plating isn’t suitable for rough, uneven, or poorly machined surfaces, and parts will need to be cleaned of soaps, oils, and dirt before the plating process can begin.

Different types of electroless nickel plating coatings are categorized by the percentage of phosphorus in the alloy by weight. Different levels of phosphorus content also offer different levels of corrosion resistance and hardness:

• Low phosphorus nickel (2 – 4% phosphorus): Low phosphorus electroless nickel has an as-plated hardness between 58 and 62 Rc, and is highly resistant to wear. It has a high melting point and good corrosion resistance when exposed to alkaline conditions. Low phosphorus electroless nickel deposits are compressively stressed and are usually more expensive than medium and high phosphorus nickel.
• Medium phosphorus nickel (5 – 9% phosphorus): Medium phosphorus nickel plating offers a middle ground between low and high phosphorus nickel. It is resistant to corrosion in alkaline and acidic environments and has a fast deposition rate (18 to 25 µm per hour). The as-plated hardness of medium phosphorus nickel can be anywhere between 45 and 57 Rc, and the plating can be heat treated to reach 65 to 70 Rc.
• High phosphorus nickel (>10% phosphorus): Since high phosphorus deposits of electroless nickel plating are amorphous, parts won’t end up with phase boundaries or grain, increasing their corrosion resistance and making them ideal for use outdoors or in extreme environments. High phosphorus electroless nickel plating also offers ductility, high thickness, and stain resistance, and will make it easier to polish or solder your final product.

Zinc Plating

Zinc plating, or zinc chromate, is a popular chemical finish that protects steel parts from moisture and corrosion. Zinc-plated products have increased longevity, improved aesthetic appeal, and a more uniform appearance. Zinc plating can also alter a part’s color to silver-blue, yellow, black, or green. Another significant benefit of zinc plating is its potential to protect a part’s surface for years: even if the coating becomes scratched, the zinc will react to the atmosphere and quickly oxidize. Since zinc is chemically susceptible to acids and alkalis, however, zinc plating may not be sufficient for parts destined for wet or extremely humid environments.

There are a few different types of zinc plating. Electro-galvanization requires an electrical current to coat the part in a thin layer of zinc, whereas hot-dip galvanization requires parts to be submerged in a hot zinc bath. Electro-galvanization is the cheaper process, but hot-dip galvanization is better for parts that will be used in aggressive environments or that will experience a lot of wear.

Following the zinc plating process, parts can undergo a secondary procedure for increased protection and improved performance. The ASTM B633 standard, the most widely used standard for zinc plating, includes four types of zinc plating:

• Type I: Type I has no supplementary treatment.
• Type II: Type II involves a colored chromate treatment.
• Type III: Type III uses a colorless chromate treatment.
• Type IV: Type IV uses a phosphate conversion treatment.

Achieving Quality Finishes With SyBridge

Chemical finishing offers numerous ways to achieve the surface quality and performance levels that you need for your part, but not every finishing process will be suitable for every material and end-use. To determine which chemical finish is right for your part, you’ll need to have a strong understanding of critical factors, such as how much corrosion, friction, and wear resistance your final part needs, the environment in which it will be used, and its required conductive or insulative properties. 

Given the importance of those considerations, it’s worth finding a manufacturing partner to help you select a suitable finish, and ensure that it offers the best quality and cost efficiency possible. At SyBridge, our expert team of designers and engineers can offer insight not just into the chemical finishing process, but material selection, tooling, and suitable CNC technologies. If you want to know more about the finishing options available for your next CNC machining project, get in touch with us today. If you’re ready to get started, create your account, upload your designs to get an instant quote, and start making new parts and products in just a few simple steps.

The post A Guide to Chemical Finishes for CNC Machined Parts appeared first on SyBridge Technologies.

The post-processing stage of a CNC machining project is arguably one of the most crucial, as it preps and puts the finishing touches on your part. There are numerous post-processing options available, and determining which is best for your part depends largely on what material it’s made of and the purpose of the part.

Passivation is one of many final treatment options for materials that can significantly improve the quality and performance of a machined part by creating a protective layer that safeguards the part against corrosion.

What is Passivation and How is it Used?

Passivation is a chemical finishing process often applied to materials such as stainless steel, but it may also be used on other alloys and metals, including aluminum. After being thoroughly cleaned to remove debris or other potential impurities, an oxidizing agent, typically nitric acid or citric acid, is applied to the material’s surface, creating a passive oxide film that strengthens its corrosion resistance.

While stainless steel is inherently corrosion-resistant due to its higher chromium content than other alloys, it is still susceptible to rust over time, especially if iron contaminants on its surface are exposed to water. This oxidation can create rouging, which displays as reddish-brown deposits on stainless steel. Etching, pitting, and frosting may also be signs of localized corrosion that should be addressed before they cause operational issues.

Passivation can help deter the development of rouging and rust, and when done correctly, it can even be used as a proactive measure to reduce the need for frequent maintenance.

Practical applications of passivation

The passivation of parts used in highly regulated systems in the aerospace and medical industries is vital due to the critical roles these parts often play. When there is little room for error, components must perform optimally, and passivation has a crucial role in enhancing the lifespan and operation of a part.

For example, the pharmaceutical and medical industries operate under strict regulations to ensure patient and product safety. Maintaining a pristine environment and using precise, high-grade tools are of the utmost importance. Therefore, many components must undergo passivation to decontaminate and to guard against rust and other corrosion.

Below are just a few other practical applications where passivation can be used to discourage corrosion:

• Food processing equipment
• Surgical instruments such as stents, forceps, and implants
• Pharmaceutical products such as inhalers
• Motor vehicle parts such as frames, bushings, and cylinder heads
• Electronic and microelectronic components
• Machine parts such as fittings, housing, and suspension arms

Passivation offers a way to control the quality of your end product so you can have confidence in knowing the parts you’re using will last.

Benefits and Drawbacks of Passivation

Passivation is a practical, precautionary measure that can extend the lifespan of parts and their systems. However, while there are not many, there are a few drawbacks to the passivation process to keep in mind:

• Passivation does not smooth out the metal, so if that is required for the final product, it will need to be addressed prior to treatment.
• Passivation requires a rigorous pre-cleaning process before treatment, which can marginally extend the time to complete the fabrication process.
• Passivation techniques can leave room for error when not applied professionally, rendering the treatment futile.
• If passivating a system regularly as part of a proactive approach to maintenance, downtime must be allotted for treatment application.

The main benefit of passivation is corrosion resistance, but there are a few other additional advantages:

• Passivation offers increased corrosion resistance, leading to longer-lasting machinery that can operate at peak performance for longer periods.
• Passivation reduces the frequency of maintenance as well as the degree of care needed.
• Passivation eliminates surface contamination that can seep into other parts of the system and even contaminate the final product.
• Passivation helps ensure the operating efficiency, quality, and safety of parts and systems over time.

Why Passivate CNC Machined Parts?

Passivation should be considered a post-fabrication best practice for CNC machined parts. While passivation does occur naturally in chromium-rich alloys such as stainless steel, welding, machining, and engraving during the fabrication process can introduce contaminants that compromise the metal. Passivation’s multi-step process involves rigorous cleaning to remove impurities such as free irons that can make the parts susceptible to corrosion.

For heavily regulated industries that require meticulous precision and tighter tolerances, such as the CNC machining of aerospace parts, passivation is not only good practice — it’s essential for increasing the durability, safety, and reliability of components.

Boost Your Parts’ Longevity with Passivation

Passivation can be necessary to ensure the resiliency of your parts, systems, and product quality. Working with a team of specialists who understand the passivation process and are meticulous about their services will ultimately determine the effectiveness of your passivated components.

At SyBridge, we understand that precision and reliability are critical. With our team of experts on your side and advanced digital tools that make manufacturing easier, your parts can go from design to delivery with accuracy and speed. To get started, create an account to put the power of cloud manufacturing at your fingertips or contact us to learn how SyBridge can optimize your manufacturing operations.

The post Passivation: Post-Processing for Rust and Corrosion Prevention appeared first on SyBridge Technologies.

Traditional metal surface finishing is the process of using an abrasive paste, wool berets, and polishing sponges to finish the surface of a metal part or component after it has been machined. The goal of polishing is to remove scratches, nicks, and other surface defects created during the machining process, while also improving the shine and appearance of the surface.

However, polishing metal parts serves more than a purely aesthetic purpose. Many metal surfaces will tarnish with time, typically as a result of exposure to oxygen, high temperatures, and use. The reflective surface achieved through metal polishing not only improves the aesthetics of the part, but helps to prevent contamination caused by corrosion, oxidation, and other forms of quality degradation.

There are three primary types of metal polishing in use today — mechanical, chemical, and electropolishing — and each offers advantages and drawbacks that must be taken into consideration. If you’re not sure of the differences between these three metal surface finishing techniques, or which one is best suited for your project, this article will help.

Mechanical polishing

The mechanical polishing process involves using physical tools and abrasives to remove grinding lines, scratches, pits, and other flaws from the metal surface. Common materials used include abrasive media, flat wheels, sandpaper, wool berets, polishing sponges, and more. For ultra-precise polishing, turntables capable of high-speed rotation and other specialized auxiliary tools may be necessary. Sometimes manufacturers use mechanical polishing as a preliminary step before electropolishing.

While mechanical polishing is precise and produces high-quality surface finishes, it is a specialized process that requires a skilled and knowledgeable technician in order to achieve the best results.

Chemical polishing

In contrast to mechanical polishing, the chemical polishing process obtains a smooth surface finish by immersing the workpiece in a chemical solution, which dissolves surface layers of the metal. This process smoothes and polishes micro-roughnesses on the workpiece’s surface, leaving behind a mirror-like finish free of burrs, vapor stains, and microscopic particles. Chemical polishing results in the formation of passivation layers, meaning that the metal is so free of debris and convex surface defects that it can be considered frictionless.

Electropolishing

The electropolishing process is similar to chemical polishing in that the part or component is immersed in a chemical solution. The key difference is that electropolishing applies an electric current to the workpiece’s surface that dissolves its metal ions into the electrolytic medium. The addition of an electric current allows for greater control over the amount of surface metal removed, which can be as little as microns of material.

Electropolishing is also an ideal fit for processing fragile parts or those with complex geometries that may be difficult to polish through other means. The process also produces passivation layers on the surface of the metal.

Pros and cons of metal surface finishing techniques

Mechanical polishing produces superior surface finishes with high brightness and aesthetic appearance. Surfaces that have been mechanically polished are also typically easier to clean. However, mechanical polishing is highly labor-intensive, can’t be used with fragile or complex parts, and may produce inconsistent or short-lived gloss if not performed properly. Mechanically polished parts are also more susceptible to corrosion.

Chemical polishing, on the other hand, can be used to polish workpieces and components with complicated shapes. It’s a highly efficient process, allowing for multiple workpieces to be polished simultaneously, and typically requires less investment in specialized equipment.

Chemical polish produces good corrosion resistance but can lead to inconsistent brightness across the surface of the workpiece. The chemical polishing solution can also be hard to heat to the proper temperature, is difficult to adjust and regenerate, and may emit harmful substances as part of the process.

Electrochemical polishing creates a smooth, bright, and long-lasting luster that is resistant to corrosion and wear and has consistent coloration throughout the part. Electrochemical polishing is low pollution and low cost but typically involves large equipment investment and additional, complex steps before the process can be performed.

If you’re trying to weigh the pros and cons of electropolishing vs mechanical polishing, there are a few things to keep in mind. Due to its speed and affordability, electropolishing is more often used for rapid prototyping. Polished metal that goes through the electropolishing process is highly lustrous, which makes it easier to visually identify any remaining surface defects. While mechanical polishing can achieve extremely high-resolution surface finishes, doing so is labor-intensive and requires highly skilled operators.

In addition, mechanically polished parts may not be usable in high-purity applications, as abrasives and other compounds may become embedded within the material of the part, which can also negatively impact the workpiece’s mechanical strength. Physical and chemical methods of polishing can result in the impregnation of particles or other contaminants in the surface, which limits cleanliness. The criterion for cleanliness is dependent on the application, but this can be a significant drawback for mechanical and chemical polishing. In applications where cleanliness is critical, like medical devices, electropolishing is often preferable for this reason.

Get started with metal surface finishing

Metal surface finishing techniques help ensure that workpieces and part components have strong, lustrous surfaces that are free of imperfections. Mechanical, chemical, and electrochemical polishing processes have different benefits and drawbacks, so it’s critical that product teams choose the right technique for a given project. SyBridge Technologies brings extensive experience to the table, including guidance and insight into choosing the best metal polishing finish for your parts. Contact us today to get started.

The post Comparing Different Types of Polishing Surface Finishes appeared first on SyBridge Technologies.

Injection molding is a popular manufacturing method that helps product teams create extremely accurate and consistent components across high-volume production runs. Injection molding is a fast, cost-effective, and versatile process that’s adjustable to your production needs and compatible with many different materials.

After the injection molding process is complete, you have many different post-processing and finishing options to choose from. Injection molding post-processing improves a part’s appearance, removes aesthetic flaws, and even provides additional mechanical properties like enhanced strength or electrical conductivity. In this article, we’ll go over some of the post-processing options for injection-molded parts that SyBridge offers.

Injection Molding Surface Finish Standards

SyBridge offers finishing options that can match any SPI standard. The Society of the Plastics Industry (SPI) defines the standards for the plastics industry, including the cosmetic quality of plastics. This includes the type of polish or finish used on plastic injection-molded components.

The injection-molded part SPI surface finish standards go from most fine to least fine, following an alphabetical grading system:

• A – Glossy finish from Grade #3, Grade #6, or Grade #15 diamond buffing
• B – Semi-glossy finish from 600, 400, or 320 grit paper
• C – Matte finish from 600, 400, or 320 stone tooling
• D – Textured finish from dry blast using glass beads, # 240 oxide, or # 24 oxide

Surface appearance, tactile quality, and production costs will differ based on the SPI level. For instance, the more highly polished finishes will drive up costs due to the increased tooling and precision required. SyBridge can produce any SPI standard for a glossy, matte, rough, or very rough injection molding surface finish.

Popular Post-Processing Options for Injection Molding

Along with SPI standard finishes, SyBridge also supports various injection molding post-processes.

Mold-Tech Textures

Mold-Tech enables texturing, which is when specific sections of a part are textured differently than the rest of the component. In order to achieve proper texturing, Mold-Tech will apply a texture onto the injection mold’s surface, then directly impress that texture onto the part during the injection molding process. Texturing can be applied to the injection mold in a number of different ways, from etching it in a chemical bath to engraving the texture by hand or with a laser.

Mold-Tech is the industry standard for textures, boasting over 500,000 options and even supporting new texture designs. You can request a Mold-Tech finish — such as sand, satin, leather, woodgrain, or any other — and then ask for a specific texture specification. These specifications are determined by series numbers, such as MT-11240. Each series number is accompanied by texture depth (inch), texture depth (meter), and draft angle.

Pad Printing

Pad printing is used to print text, images, and colors onto products with round, concave, and recessed or raised areas. A silicone pad transfers a 2D image from a laser engraved printing plate onto the 3D object by pressing an ink plate into it before it’s stamped by the silicon pad. Pad printing is a fast, inexpensive method of printing onto all kinds of complex shapes like cylinders, curves, spheres, compound angles, and even extreme textures.

Silk Screening

Silk screening is a very common printing technique used to add images, text, logos, and other details to a component. The design is first printed out onto a sheet and placed into a frame, and then the frame is placed onto the part. A scraper moves colored ink, paint, or another dye across the screen. The screen is then removed, leaving a thin layer on the part that displays the design.

Silk screening offers great quality to price ratio for large production runs, and the silkscreens themselves are incredibly durable and reusable. The silk screening process allows for creativity, fine detail, and incredible customization.

Heat Stake Inserts

Heat stake inserts enable you to put metal inserts and fasteners into the component, which reduces complexity. The process begins by heating up metal threaded inserts so they can bond to already injection-molded parts, then using heat to quickly melt the surrounding plastic and push the threaded insert into place. Heat stake inserts eliminate the need for small consumables like rivets and screws, which streamlines the process.

Ultrasonic Welding

This uncommon post-processing technique is designed to join parts together using a solid-state weld. Ultrasonic welding is useful when bonding two plastics together or when working with other dissimilar objects that have trouble bonding. During the ultrasonic welding process, the two components are held together in a fixture under pressure. Then, high-frequency ultrasonic acoustic vibrations are played through a vibrating tool called a horn. The frictional heat generated from the vibrations melts the substrate, creating a localized weld area that joins the two parts together.

Ultrasonic welding doesn’t require any fasteners like bolts or nails, soldering materials, or adhesives. Like heat stakes inserts, ultrasonic welding reduces set-up time and costs and reduces opportunities for corrosion, fastener stripping, or other long-term issues. Ultrasonic welding is a fast and efficient finishing process that is easily repeatable, requires little clean-up, and takes mere seconds to complete. However, product teams should know that this post-processing option is a rare and specialized solution that might not be suitable for many products.

Finish Your Injection Molding Jobs With SyBridge

Product teams have many different options when it comes to injection molding surface finishes. SyBridge supports SPI standard finishing options that determine surface roughness, along with aesthetic finishes like texturing, color matching, and design or text transfer. We also offer injection molding post-processing options that improve part functionality – such as joining parts together and increasing their durability – and painting, light assembly, and protective packaging.

An excellent surface finish can set your component apart from the competition. At SyBridge, we’re dedicated to helping you create injection-molded parts that are functional, recognizable, and long-lasting. Our expert manufacturers can guide you through the injection molding process, including finishes and post-processing procedures, so you can bring incredible final touches to your next project. Contact us today to learn more about our injection molding services.

The post An Overview of Post-Processing Options for Injection Molding Parts appeared first on SyBridge Technologies.

What is Hot Stamping?

Hot stamping is a lithography printing process that uses heated image molds or stamping dies to transfer metal foils or pre-dried inks onto a surface.

Typically, the process works as follows: the hot stamping machine heats an engraved mold or die, which then presses marking foil onto the surface. The foil is deposited only where the hot stamp comes in contact with the product material, allowing engineers to create elegant, embossed designs on parts and assemblies in post-production. Hot stamping foils have three layers: a color layer (which can be pigment or metallic), an adherence base, and a release layer. Innovations in digital printing even enable hot stamping three-dimensional images with holographic foil.

Hot stamping is a versatile, precise, and efficient method for printing on surfaces, and is often used to personalize or decorate products. Here’s a quick rundown on some of the key benefits of the hot stamping process, as well as key considerations to keep in mind.

Four Key Benefits of Hot Stamping

One of the most significant advantages of hot stamping is that it can be used to treat a wide range of common product materials — including plastics, rubbers, and metals — in addition to more specialized materials like wood, leather, and glass. Hot stamping foil can even be applied to coated objects without damaging the coating. As such, it can be effectively applied to parts ranging from pencils and book bindings to cosmetic packaging and cable ties.

Benefit #1

Hot stamping is also a clean and incredibly effective process. Because hot foil stamping machines work with rolls of metal foil or pre-dried inks, engineers can avoid mixing liquid inks and cleaning up messy spills.

Benefit #2

Hot stamping also consistently produces high-quality results — regardless of the pigment or metallic coloration of the foil, adherence bases are created to have a strong grip on product surfaces. However, some materials — such as leather — require specialty foils in order to properly adhere, which is important for product managers to keep in mind.

Benefit #3

While marking foils are designed to be durable, environmental conditions can cause them to fade over time. In instances when a metal die is pressed into plastic or wood parts, the die can actually brand the material, ensuring that a mark remains even if the foil wears away.

Benefit #4

Though primarily used as a finishing process, the hot stamping method has other applications, as well. For instance, in automotive manufacturing, hot stamping can be used to maximize steel malleability. The process is similar to warm forming; however, the dies are cold when pressed into the heated steel, which creates Martensite microstructures in the steel that give the part exceptional strength. This makes hot stamping useful in the production of strong vehicle cabins and safety cages, among other parts.

Hot Stamping Limitations and Considerations

The one significant limitation of the hot stamping foil manufacturing process is that it does not allow for printing extremely small letters without losing definition. Otherwise, so long as the design can be made into a mold or die, it can generally be used to transfer stamping foil without issue. If high-definition small lettering is required, pad printing or screen printing may be more suitable options.

Another key consideration is the choice of material for the die that presses the stamping foil. Metals like brass, copper, magnesium, and steel are commonly used. Magnesium dies are easiest and least expensive to make but are less durable. Copper and brass offer greater durability and require greater costs to produce, while hardened steel dies are virtually indestructible and provide the best foil transfers. Steel dies are expensive to produce, but due to their durability, become incredibly cost-effective when used in high-volume production runs.

Hot stamping products that feature complex shapes or surfaces that aren’t perfectly flat presents a challenge. However, manufacturers often overcome this hurdle by using silicone-based stamping dies. Because they are inherently softer than metal stamps, silicone dies conform better to irregular surfaces or shapes, which enables more precise transfers.

Comprehensive and Unparalleled On-Demand Manufacturing Service with SyBridge

Ultimately, hot stamping is an effective means by which to customize or embellish parts, or to increase the malleability of materials such as steel. In any case, the process is versatile and relatively simple.

Product teams hoping to leverage hot stamping in their next project should look no further. SyBridge works to expand the boundaries of what’s possible with modern manufacturing. Our team of engineers and designers work closely with every customer during each stage of the production lifecycle — from design to post-production finishing. We create more than parts — we build trusting partnerships focused on manufacturing superior components and assemblies on-time, every time. We can even update legacy products using newer, innovative manufacturing methods. Contact us today to start your next product run.

The post Everything You Need to Know About Hot Stamping appeared first on SyBridge Technologies.

Surface finishing is the final step of CNC machining. Finishing can be used to remove aesthetic flaws, improve a product’s appearance, provide additional strength and resistance, adjust electrical conductivity, and much more.

With all of the surface finishing options available, how can product managers and designers make sure they’re choosing the best one? Luckily, there are a few common finishes that offer unique advantages, and it’s just a matter of understanding the specifications of each option.

Common Finishes for CNC Machined Parts

As-Machined

CNC machining produces a part with an “as-machined” or “as-milled” finish as soon as the manufacturing process is completed. The part will have small but visible tool marks and blemishes. The average surface roughness is around 3.2 μm. As-machined parts have the tightest dimensional tolerances and are extremely affordable to produce because post-processing isn’t necessary.

This finish is a good choice for those who are more concerned with dimensional integrity than aesthetics. However, parts with as-machined finishes don’t rank very highly when it comes to protection. Their roughness and lack of protective coating renders them susceptible to nicking, scuffing, and scratching.

Anodizing

Anodizing is an electrochemical process that thickens a CNC machine part’s natural oxide layer to make it thicker, denser, electrically non-conductive, and more durable.

This process can only be done using aluminum or titanium alloys because they conduct electricity well. During anodizing, the alloy is submerged in an acid electrolyte bath and acts as an anode. Once a cathode is placed in the anodizing tank and an electrical current passes through the acid, oxygen ions from the electrolyte and atoms from the alloy combine at the surface of the part.

Anodizing comes in two different varieties — Type II and Type III. The overall finishing process is the same, but Types II and III require that the part be submerged in a diluted sulfuric acid solution.

Anodizing Type II, also known as “decorative anodizing” (as the finished coating can be clear or colored), produces coatings up to 25 μm thick. The coating thickness range for clear parts is 4-8 μm and 8-12 μm for parts that have been dyed black. This process produces a part that is smooth, elegant, and resistant to corrosion and wear.

Anodizing Type III, also known as “hardcoat anodizing,” can produce anodic coatings up to 125 μm thick. Parts with this coating have high density and are even more wear-resistant than anodizing Type II.

All in all, anodized finishes are durable and promise good dimensional control. Anodized finishes are best used in high-performance engineering applications, particularly for internal cavities and small parts. They are among the most aesthetically pleasing finishes for CNC machined parts, but often come at a higher price tag.

Powder Coating

Powder coating is a lot like spray painting. First, the part is primed with a phosphating or chromating coat to make it more resistant to corrosion. Then, the part is “painted” with a dry powder coating from an electrostatic spray gun and cured in an oven heated to at least 200°C. Multiple layers can be applied to increase thickness, which can reach 72 μm.

On its own, this finish creates a thin protective layer on the CNC machined part that is strong, wear-resistant, and aesthetically pleasing. This process can be combined with bead blasting to increase the part’s corrosion resistance and create greater uniformity in texture and appearance.

Unlike anodizing, a powder-coated finish is compatible with all metals, less brittle, and offers greater impact resistance. This finish is suitable for many functional applications but may be particularly well-suited for military applications.

However, powder coating generally yields less dimensional control than an anodic finish, and powder coating is not recommended for use in small components or internal surfaces. What’s more, powder coating’s higher price point might make it prohibitively expensive for larger production runs.

Bead Blasting

Bead blasting is used to add a matte or satin surface finish to a CNC machined part. During this process, a pressurized air gun shoots millions of glass beads at the part, effectively removing tool marks and imperfections, creating a consistent grainy finish. In contrast to other finishes, including anodizing and powder coating, bead blasting adds no chemical or mechanical properties to the part — it’s purely visual. Unlike powder coating, which adds material to a part, bead blasting is a reductive finish, meaning it removes material from the part. This is an important consideration if your part has strict tolerances.

Bead blasting is one of the most affordable surface finishes, but it must be executed manually. As such, those considering bead blasting as a surface finish should be prepared to incur the cost of engaging an operator who has been formally trained in this process, and recognize that the final result will largely depend on how skilled the operator is. Bead size and grade will also affect the final finish.

Gain Expert Advice on Finishing Your CNC Machined Parts

In short, a post-processing finish such as anodizing or powder coating will likely prove an effective option for parts that don’t need to be picture-perfect but must maintain their original dimensions. Protecting or reinforcing an aluminum or titanium part may benefit from anodizing. If the part cannot be anodized but requires strength and impact resistance, powder coating provides an effective alternative. Finally, if cost-effectiveness is a higher priority than tolerance — and the part does not require a glossy finish — bead blasting may be the preferable route.

Engineers, designers, and product managers would do well to consult a manufacturing expert to ensure they are making the right choice for their next project. The experts at SyBridge are well-versed in all things manufacturing, from product design and prototyping to manufacturing at scale. Our team can help you choose which finish is best for your CNC machined part and make sure you go to market with a strong, elegant finished product. Contact us today.

The post Choose the Best Finish for Your CNC Machined Part appeared first on SyBridge Technologies.