Month: March 2025

The majority of parts made using injection molding are rigid plastic components. Typically, these parts are made from thermoplastics like ABS or PC, with different plastics offering different material properties to suit different applications.

However, injection molding can also be used to make flexible moldings: parts that are soft, pliable, shock-absorbing, ductile, or elastic. Products like hand grips, gaskets, protective smartphone covers, and certain medical implants all require a rubber-like material in order to perform their function, and injection molding offers two standout material options for making such products.

The first of these materials is liquid silicone rubber (LSR), a thermoset that requires its own special variant of the injection molding process. The other is a group of thermoplastics known as thermoplastic elastomers (TPEs), which can be processed like common rigid thermoplastics but which offer rubber-like properties.

This article examines the LSR vs TPE injection molding discussion, comparing material properties, advantages and disadvantages, and suitable applications.

What is liquid silicone rubber (LSR)?

Liquid silicone rubber is a high-purity form of cured silicone. It is a chemically inert thermoset with material characteristics such as biocompatibility, chemical resistance, water resistance, excellent compression set, flame retardancy, and heat resistance up to 250 °C.

Injection molding LSR requires a special process generally known as liquid silicone rubber molding. Unlike a standard injection molding machine, the equipment comprises a metered pumping device for dispensing the two liquid materials (catalyst and base forming silicone) and a mixer for combining the materials before they enter the mold. The mold cavity is heated, allowing vulcanization of the silicone to take place within the cavity.

What are thermoplastic elastomers (TPEs)?

Thermoplastic elastomers or thermoplastic rubbers are a class of thermoplastics exhibiting both thermoplastic and elastomeric material properties. Because they are thermoplastics, they are easier to manufacture than other rubber-like materials, being highly suited to injection molding and extrusion-style 3D printing.

TPEs have good thermal properties, good stability, and require minimal energy to manufacture. They can also be easily recycled, as TPE parts can be melted down without burning.

Some of the most common types of TPEs are:

• Thermoplastic polyurethanes (TPU): good clarity, good wear resistance, range of hardnesses
• Thermoplastics vulcanizates (TPV): matte finish, high compression set
• Styrenic block copolymers (TPS): highest level of flexibility among TPEs
• Polyolefin blends (TPO): tough, good impact strength
• Thermoplastic copolyesters (TPC): good tear strength, impact strength
• Thermoplastic polyamides (TPA): high temperature resistance, low compression set

LSR injection molding vs TPE injection molding

Both liquid silicone rubber and thermoplastic elastomers have their own unique advantages as injection molding materials. In short, LSR offers superior elastomeric performance in addition to chemical advantages, while TPE is easier and more convenient to process.

LSR advantages

TPE advantages

Very high temperature resistance

Compatible with standard injection molding machine

Biocompatibility for medical and food applications

Re-moldable and recyclable

High level of tear strength

Fast, simple, and less expensive molding process

Superior chemical resistance

Easy to add color with pigments

Minimal warping even with uneven wall thicknesses

Heat sealable

Superior compression set

Pellets easy to handle

LSR injection molding applications

Although the liquid silicone molding process requires specialist equipment and requires longer molding cycles than thermoplastic injection molding, the unique benefits of LSR — such as its exceptional compression set — give it a number of important applications, from healthcare to industry.

Some injection molded silicone part examples include:

• Silicone medical implants such as orthopedics, cardiovascular stents, pacemakers, lenses, and soft tissue implants
• Medical devices such as surgical instruments and drug delivery devices
• Headphone and hearing aid tips
• Baby bottle tips
• Shower heads
• Electronic device components such as keyboard interfaces
• Electronic device protective covers and skins
• Watertight gaskets
• Heat-resistant and UV-resistant automotive components such as O-rings, bellows, and stoppers

TPE injection molding applications

Injection molding thermoplastic elastomers requires the same equipment and process as standard thermoplastics, making fabrication of TPE moldings fast, affordable, and simple. The material also offers important material properties, which can vary greatly depending on the type of TPE chosen.

Some injection molded thermoplastic elastomer part examples include:

• Soft-touch grips for handheld tools and devices (sometimes via overmolding)
• Certain food products such as bottle cap liners
• Electronic device components such as enclosures
• Electronic device protective covers and skins
• Shoe soles
• SCUBA flippers
• Wheels for skates and skateboards
• Sealing rings
• Automotive components such as suspension bushings

Design considerations

Although both LSR and TPEs can be injection molded, different design rules apply to the two materials.

Overall, LSR offers greater design freedom than thermoplastics like TPEs, mostly due to its extreme flexibility. Because silicone moldings are highly pliable, part ejection is simple: the soft part can usually be removed manually from the cavity without the use of ejector pins. Protruding undercuts are generally no problem either, as these sections can be squashed or bent around the corner of the mold.

Furthermore, because liquid silicone flows easily, product designers can be more liberal with uneven wall thicknesses — features that would potentially cause filling or warping issues with thermoplastics like TPEs. However, one advantage of TPEs over silicone is that the higher viscosity of the thermoplastic makes it less likely to leak out at the parting line and cause flash. Silicone molds require effective sealing and clamping to prevent flash.

3ERP offers a range of injection molding services, including plastic injection molding, silicone injection molding, and metal injection molding. Request a free quote for your next batch of flexible molded parts.

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Fundamentally, you need precision machines. If your machine tolerance is +/- 0.05mm, but you try to make some parts with +/-0.01mm tolerance, that’s not going to happen for sure. An ant won’t be able to lift an elephant.

Once you have precision machines ready, does that mean you can start to make precision parts? Not yet. Then, you need to invest good tool holder and tools. A good tool holder that you can install tools precisely. Normally, we will keep the concentricity around +/- 0.005mm.

With all these equipment and very experienced engineers who can sort out the best way to make a prototype parts and production including set up the proper fixture, optimize the tool path, avoid deformation, etc. To ensure all parts are done right in one go.

The on-site inspection system also helps a lot during manufacturing. We know exactly if the actual parts on the machine are good or not. And the system will adjust the tool path base the inspection result. If we found problem on half way, and it is not possible to fix, then we won’t invest time to continue further steps.

Learn more about our CNC milling services

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Chrome plating is a popular finish for metal objects, but it can be difficult to remove if you need to change the color or appearance of the metal underneath. There are a few different methods to remove chrome plating, depending on the type of metal and the amount of chrome that needs to be removed.

Sometimes this is a task that can easily be carried out at home, but often it’s best to let the professionals handle it. Some methods may require special equipment or chemicals, so it’s essential to do your research before starting the removal process.

What Is Chrome Plating?

Chrome plating is a process in which a thin layer of chrome is applied to a metal surface. The chromium layer provides a shiny, reflective finish as well as increased resistance to corrosion and tarnishing. Chrome plating is often used on car parts, such as bumpers and wheels, but it can also be used on household fixtures, such as door handles and other fixtures.

What Process Is Used in Chrome Plating?

The chrome plating process uses electroplating, a way to use electricity to coat one metal with another. In this case, the metal being coated is usually steel or aluminum, and the coating is chromium.

The part that will be chrome plated is first cleaned and then placed in a solution that contains chromic acid. An electrical current is passed through the solution, and this causes the chromium atoms to adhere to the surface of the metal. The thickness of the chromium coating can be controlled by adjusting the amount of time the part spends in the solution.

After the desired thickness is achieved, the part is rinsed and then heated so that the chromium forms a strong bond with the surface of the metal.

Why Would You Want to Remove it?

If the metal underneath is damaged, it may be necessary to strip off the chrome plating to repair it. In other cases, the chrome plating may simply be worn or scratched, and it may be necessary to remove it to apply a new layer.

Potential Hazards Faced When Removing Chrome Plating by Yourself

Before attempting to remove chrome plating, you should be aware of a few potential hazards. Gloves, goggles, and respiration masks are essential to protect yourself from the chemicals used in the process. Inhaling fumes from the chemicals can be dangerous, so it’s important to work in a well-ventilated area. You should also avoid getting solutions on your skin.

Another hazard to be aware of is the potential for creating electrical shocks. When working with electrical currents and chemicals, electrocution is always a risk. Be sure to take all necessary safety precautions.

Chrome Plating Types

There are two types of chrome plating: decorative and hard.

Hard Chrome Plating

Hard chrome is a thick layer of chromium that is applied to a metal surface to provide increased wear resistance. It is often used on tools and machine parts subject to high friction levels. Due to its thickness, hard chrome is more difficult to remove than decorative chrome.

Decorative Chrome Plating

In contrast, decorative chrome is applied with a thin layer of chromium to the surface of the metal to provide a shiny, reflective finish. It is often used on car parts and household fixtures, providing protection but mainly for its aesthetic appeal. In most cases, decorative chrome is easier to remove than hard chrome plating.

Ways to Remove Chrome Plating From Metal

Now that you have a primer on all things chrome plating, it’s time to learn about the different ways that you can remove it. As we mentioned before, chrome plating is applied using an electroplating process.

There are a few methods that can be used to remove chrome plating from metal, and we’ll go over each one in detail.

Specialist Equipment

The first method is to use specialist equipment. This is the most expensive option but also the most effective. If you decide to go this route, find a reputable professional with experience removing chrome plating.

Abrasive Blaster

Abrasive blasting uses high-pressure air to propel abrasive particles such as sand, glass beads, or steel shot against a surface. This process can be used for various purposes, including removing paint, rust, or other deposits.

Abrasive blasters are a common sight in body shops, where they are used to remove chrome or other finishes from car parts. The high-pressure stream of abrasive particles strips away the chrome coating, leaving the metal surface exposed and undamaged.

Abrasive blasting is generally safe when done correctly, but some risks are associated with the practice. These include inhalation of dust particles, eye injury from flying debris, and skin irritation from exposure to the blasting material.

Ultrasonic Cleaner

The other specialized equipment method that can be used to remove chrome plating is an ultrasonic cleaner. Typically used for cleaning delicate electronic parts or jewelry, ultrasonic cleaners use high-frequency sound waves to remove dirt, grime, and other deposits from surfaces.

When it comes to removing chrome plating, ultrasonic cleaners work by causing the chromium particles to vibrate at a high frequency. This process breaks the bond between the chromium and the metal surface, causing the chrome to flake off.

The main advantage of using an Ultrasonic cleaner is that it is a gentle method of chrome removal and easy to use. However, unless you have ready access to an ultrasonic cleaner, the expense of investing in one may not be worth it for a one-time chrome removal project. In addition, because they are limited in size, you can only use them to remove chrome from small objects.

Using Chemicals

The next method that can be used to remove chrome plating is using chemicals. While chemicals are a less expensive way to remove chrome plating, they should also be handled with extreme care as they can be dangerous. Protective clothing and gloves are a must when working with these chemicals.

Hydrochloric Acid

Also known as muriatic acid, hydrochloric acid is a corrosive material used for various purposes, including cleaning masonry and removing rust. It is also an effective way to remove chrome plating from metal.

An acid solution with a 30–40% concentration should be enough to remove chrome.

The process is simple enough, taking care to avoid skin contact.

1. First, you’ll need to dilute the hydrochloric acid with water in a ratio of 1/3 part acid to 1 part water. You’ll need a heavy-duty metal bucket or another suitable chemical-friendly container to mix the two together.
2. Put the chrome-plated item in the solution and let it soak there until the chrome comes off.
3. Once the chrome has been stripped away, remove the item from the bucket and rinse it off with clean water and soap.

Sodium Hydroxide

You might know sodium hydroxide by the more common name of lye or caustic soda. It is used in various ways, including making soap, unclogging drains, and in this case, an effective way to remove chrome plating from metal.

We should strongly point out that if the base metal is aluminum, and the sodium hydroxide is mixed with water to form a solution, it can give off hydrogen gas. This is highly explosive and should be avoided at all costs.

The process for using sodium hydroxide to remove chrome plating is similar to that of hydrochloric acid.

1. First of all, mix between 8 to 12 fl ounces/227 ml to 355 ml of sodium hydroxide with a gallon of water or 3.785 L. Using a container made of neutral material is crucial, like a heavy-duty plastic bucket, as lye is corrosive.
2. Soak the object in the mixture, ensuring it is completely submerged. This could be a slow process, so regularly check to see if the chrome has started to come off.
3. Once the chrome is stripped away, remove the item from the bucket, clean it with soap and water, and rinse and dry.

Reverse the Electroplating Process

The final method we will look at for removing chrome plating using chemicals is to reverse the electroplating process. It involves a live current, sulphuric acid, and chromic acid; for this reason, it is the most dangerous of the methods discussed and could result in serious injury.

This method should only be attempted by someone with a working knowledge of electricity and chemicals. Toxic and carcinogenic fumes will be given off during the process, and with the live current, there is a serious risk of electrocution.

To briefly summarize the process:

1. The chromic and sulphuric acid are mixed in water to make the solution.
2. The solution is then heated to a temperature determined by the type of chrome plating being reversely electroplated, and from a DC power source, a negative charge is run through the solution.
3. The object to be stripped is connected to a positive cathode, which is then immersed into the solution.
4. The process takes place until the chrome is removed. The object is then rinsed, and the chemicals should be disposed of professionally.

Removing Chrome Coating Using Everyday Household Products

If you want to avoid using any of the dangerous chemicals that we have looked at, there are some methods that make use of more common household products.

Baking Soda

Baking soda is one of the most versatile products to have in the home. If the chrome is thin, you can use it as an abrasive to simply scrub away the chrome plating.

Make a paste using baking soda and water, apply it to the chrome surface, and rub it with a cloth or brush. Stop and check your progress from time to time to ensure you don’t scratch the underlying metal surface.

Bleach

Another option for using a product often found in the home is bleach—soaking the item you want the chrome removed from in a bleach bath for a day or so should do the trick if the chromium plating isn’t too thick. Ensure you dispose of the bleach after use, don’t reuse it for anything else.

In Conclusion

We hope that this article has given you some ideas on how to go about removing chrome plating from metal. As we have seen, there are a few ways to do it, some using everyday household items, others using more dangerous chemicals or specialized equipment. The method you choose depends on the item you want to strip and how comfortable you are working with chemicals.

One final word of advice, if you are unsure about any of the methods or chemicals used in this article, please consult a professional before attempting to remove chrome plating yourself.