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Common Plastic Injection Molding Post Processing Methods

Injection Molding post processing is a process that occurs after the injection molding process step. It improves parts and even provides additional mechanical properties like enhanced strength or electrical conductivity to them! In this article, we’ll go over some of most popular options for improving your finished product with our services:

Here are six common types of post-processing activities:Painting, Electroplating, Laser Marking, Logo Printing, Heat Staking, Ultrasonic Welding.

Table Of Contents


What Is Plastic Painting

Painting is a form of post-process for injection molding that adds colored coatings to molded injection molded plastic parts. In this activity, the finish is applied by spraying a color onto the surface finish of the plastic parts while they are still in a heated oven.

Painting Benefits

Painting is a common post-processing method for plastic injection molding. The process hides any surface defects that are on the molded product by adding color to the surface of the plastic materials.

The Painting Process

This can be done by either an airless or a manual spray gun. This is usually done with an airless or manual spray gun in a controlled environment to avoid overspray and part damage which can occur when paint begins to dry. Some painters apply heat to the plastic parts before painting them, which improves adhesion and improves through-film drying time.

Plastic Product Painting
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There Are Two Common Parts-Painting Methods

Spray Painting

Spraying is the simplest manufacturing process and can use self-curing paints that air-dry. Two-part paints that cure with ultraviolet (UV) light are also available. In this process, the paint is atomized into very small particles that are then deposited on the surface finish of the plastic injection molded parts. The paint should be applied in a thin layer to avoid runs and sags.

Powder Coating

Powder coating is a post-process for plastic injection molding that applies an acrylic powder to the surface of the part. The powder is applied with electrostatic painting equipment and is heated with UV lamps to ensure surface adhesion. Powder coating helps avoid chipping and flaking, which are common occurrences with paints on injection molding plastics products!


What Is Plastic Electroplating?

The other popular option is Plating where metal deposits are put onto the flat surfaces of plastic injection molded parts after they have cooled from being injected with molten plastic.

The metal deposits help to improve the surface appearance and corrosion resistance of the part.The part is immersed in a pot containing flammable liquid, usually an organic solvent or hydrocarbon, while it is held in a vacuum container.

The container is filled with pressurized gas which removes air bubbles from the liquid while also heating it to speed up deposition of the metal.

The Plastic Electroplating Benefits

Raw plastic is the foundation of any good manufacturing processes, but it’s not always enough to keep up with corrosion and wear. That’s where plastic plating comes in!

The deposition of metal on injection molded parts improves excellent chemical resistance and appearance for plastic injection molding parts that are used in high-corrosion environments like salt spray or marine applications. 

It can be applied for a wide variety purposes like increasing part’s surface finishes hardness or promoting electrical conductivity – all while also improving appearance by making your product look more appealing on top-of-the line equipment. 

The Plastic Electroplating Process

After a series of chemical baths, the surface is cleaned and removed so that it can be chemically bonded with pure noble metals. This process results in an electroless copper coating over all exposed areas on plastic workpieces before they’re ready to go into production for additional under-plating layers depending on what’s needed by form or function within whatever parts are being created!

When the plastic parts are removed from the container, it must be thoroughly dried. This process can take hours because heat speeds up metal deposition but it also speeds up evaporation of the plating bath liquids.

Plastic Product Plating
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There Are Two Common Parts-Plating Methods.

Vacuum Electroplating

Vacuum coating is a technique for vapor phase coating in a vacuum chamber filled with air or an inert gas. Vacuum deposition causes a solid or liquid material to be deposited from the vapor phase onto a surface, typically at low pressures and often at room temperature. When performing polymer coating, this could mean coating a surface with a metal such as chromium.

The surface should be first sanded and cleaned, then coated with the desired material that will provide the desired properties depending on the use of the article being constructed. A vacuum is created by sealing off both ends of a rectangular cavity with porous walls through which gas can escape but not enter. The vapor-phase material is heated until it becomes less dense than air, and it fills.

Water Electroplating

Water Plating, otherwise known as wet electroplating is an ancient technique that has been used for centuries to produce beautiful metals with exceptional durability. In this process liquid metal or another safeguarded material goes onto the surface of another piece which will then be fixed using electricity in order create something new!

The water plating process is similar to electroplating. The article to be plated with metal is immersed in a solution that contains the desired metal and then connected to an electric source. This method is primarily used when there is already a coating of metal on the article, such as copper plating on brass, which will not allow for contact between the copper and the metal being plated.

What Are Some Of The Advantages Of Vacuum Electroplating?

Vacuum coating offers the following advantages:

The vacuum plating has strong adhesion, the coating is not easy to fall off

The diffraction is good, the coating thickness is uniform

The coating is dense, the pinhole bubbles are less

The treatment is easy before plating, the process is simple, the materials are used and pollution-free.  

What Are Some Of The Advantages Of Water Electroplating?

There are many advantages of water plating, including:

Increased productivity because it does not require manual operation

Lower capital costs than other types technology because technology involving water does not require expensive equipment

Low operating costs because no expensive process chemicals

Laser Marking

What Is Laser Marking?

Laser engraving marking is a manufacturing process that uses a laser to engrave text or patterns into the surface of a plastic part. It is a non-contact process, which means that it does not require any physical contact between the laser and the part being marked. This makes it an ideal marking method for plastic parts that are too delicate or fragile to be marked with other methods, such as inkjet printing or stamping.

How The Laser Marking Works?

Laser marking works by using a laser beam to hit the material. The energy from the laser creates a reaction on the surface of the thermoplastic materials that leaves a permanent mark. The speed, power, and focus of the laser beam will determine the type of laser manufacturing process that is used.

The Benefits Of Using A Laser Marking

One of the most significant benefits of laser marking is that it can be used on plastic parts that are very delicate or fragile, which other common process methods cannot. This makes it a good choice for items that require easy identification but cannot handle other types of processes, such as inkjet printing or stamping.

Direct part marking with a laser marking machine delivers durable, readable marks. The results of these high quality marks include:

  • Easy to read, even from a distance
  • Resistance to fading or erasure
  • Permanence in harsh environments
Laser marking For Plastic Product
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Logo Printing

What Is Logo Printing

Logo printing technique used to add images, text, logos, and other details to a component on the product through different printing methods. The logo can be imprinted on the surface finishes of the product with a variety of printing methods.

Plastic Product Logo Printing
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There Are Four Common Logo Printing Methods

Silk Screen

The design is first printed out onto a sheet and placed into an ornate frame. The colored inks, paints or other dyes are applied using a scraper for the screen to be moved across it before being removed leaving behind only thin sheets displaying each individual detail of your desired design masterpiece!

Screen printing is often used when the surface of the molded part is flat and a large area is needed for printing.

Pad Printing

Pad printing offers a number of advantages over other methods. It’s fast, inexpensive and can be used on all kinds tough complex shapes like cylinders or even extreme textures because pad printing doesn’t require any heating up in order to transfer the image from 2D onto 3D objects with raised areas that would otherwise become difficult if not impossible during traditional 3d-printing processes.

Pad printing is often used when the surface of the molded part is curved and requires a small area of printing

Foil Stamping

Foil stamping is the process of applying designs and text on various materials using metal foils. The shiny surface makes it popular among those who want their products to be noticed, while also being lightweight enough so as not add too much weight or bulkiness when dealing with other supplies like plastic cards for instance; this allows designers plenty opportunities in terms of design flexibility!

The stamping process is a great way to print on products with dark colored surfaces, as it does not use any ink and so will always give you an even application.

Thermal Transfer Printing

As the name suggests, heat transfer printing is a process where images are transferred to items such as plastic products by applying heated plastic film. The release layer on one side of each plastic roll melts at high temperatures, allowing for easy application into any desired position once it’s been printed with ink or airbrushed graphics before being transferred overtop by another thin lacquer coating which fuses together all toner particles in contact .

Thermal transfer printing is often used for printing plastic products with multiple color printing and gradient colors

Heat Staking

What Is Heat Stake Inserts

Heat stake threaded inserts are a type of fastener that can be inserted into components to make them stronger. This reduces the complexity of the component, and makes it easier to assemble.

The Heat Stake Inserts Process

The use of heat to quickly melt and push metal threaded insert into place is one way that cost savings can be made during manufacturing. The process begins by heating up threaded inserts so they bond with already injection molded parts, then using high temperatures (upwards 500 degrees Fahrenheit) for just seconds at time until all desired fitment has been achieved.

The Heat Stake Inserts Benefits

In plastic parts, some screw structure can not be realized by injection mold, or the cost of injection mold is too high, then it is necessary to use heat stake metal inserts process. This eliminates the need for small consumables like rivets or screws which streamlines construction tremendously! Heat staking typically out performs its competition in production costs, repeatability, strength, quality, reliability, and even throughput.

Plastic Product heat-staking-inserts
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Ultrasonic Welding

What Is Ultrasonic Welding

Ultrasonic welding is a common post-processing method that uses high-frequency sound waves to create a weld between two plastic parts. This process is often used to attach plastic parts together. Ultrasonic welding creates a strong, permanent bond and is ideal for plastic parts that require a high degree of precision.

The ultrasonic welding process
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The Ultrasonic Welding Process

The process of ultrasonic welding involves applying high-frequency acoustic vibrations to the two plastic parts in a fixture. An ultrasonic horn vibrates between 20,000 and 40,000 times per second while maintaining slight contact with the plastic resin. This vibration produces friction and, in turn, enough heat to melt the injection unit. where friction causes them together through heat generated from vibration.

The Ultrasonic Welding Benefits

As the name suggests, ultrasonic welding does not use fasteners like bolts or nails. It’s an easy and efficient process that takes seconds to complete! Unlike other methods such as heat stakes inserts which can cause corrosion in long-term issues with your project because they are heated on both sides of materials together, ultrasound only ever hit hot spots which helps reduce set up time while eliminating potential problems caused by excessive contact between joints.

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