How to Apply Appropriate Textures to Injection Molding Tools

 

Plastic parts range from cosmetic housing units to internal components that need fine polishing. However, most people give little attention to the level of the surface of finish done on the parts. Product designers consider this an essential aspect for any plastic part made. The steps taken to identify the right texture for a plastic part are complex and requires consideration of numerous factors. These factors allow the creation of complex and sophisticated plastic injection molded parts. Therefore, to quickly achieve texture on plastic surfaces, at Creatingway, we have devised several tricks. One of them is giving injection molding tools texture. This trick permits repetition and control of any desired texture on mold tools.

The Techniques Used to Apply Texture on Injection Molding Tools

• EDM Spark Erosion

Electrical Discharge Machining (EDM), also called sparked erosion, uses an electrode placed in a dielectric bath of oil or water. The electrodes used can either be copper or graphite. This process works by allowing the electrode to achieve threshold current with the release of sparks against the tool wall. The sparks melt the target with simultaneous quenching by the surrounding dielectric fluid. All this happens within a fraction of a second.

Spark erosion works well on both soft and hard metals. This process is able to maintain very tight tolerances due to the loss of little material. Also, the process is ideal for debossed lettering, sharp concave corners, and deep thin slots. Thus, it works on features that would be hard or impossible to machine conventionally. Spark erosion produces an excellent and smooth finish on the mold tools. Thus, it eliminates the need for using less affordable and time-consuming hand polishing.

• Polishing and Sanding

At Creatingway, we use rough machines to prepare some of the injection molding tools. During this process, marks may be inadvertently left behind on the tool’s surface. Unless rectified, these marks can be transferred onto the surfaces of the plastic product resulting in an undesirable effect.  Thus, to avoid this costly error, we do polishing and sanding to remove the mark and other minor surface imperfections.

We have tasked skilled professionals who know their way around several types of equipment. For instance, sandpapers, rotary tools, files, and diamond burrs. They use these tools to create a range of texture finishes on the injection molding tools. Such as mirrored surfaces to coarsely grained surfaces. However, note hand polishing produces a global effect and not a specific repeating pattern on the molding tools surface. We take extra caution during polishing and sanding not to alter the dimensional tolerance excessively. Additionally, despite our technicians’ excellent skills, they might not be able to access a fragile section or deep pockets of the mold tool.

• Media Blasting

Media blasting involves the use of a high-pressure air spray that contains dry or wet abrasive material. We use this machine on the surface of the tool wall. Types of abrasive media used include aluminum oxide, walnut shells, silica, and glass beads. The method is excellent for producing a uniform matter or satin finish on the mold tool wall. However, what determines the final outcome is the type of media, air pressure, spray pattern, and volume used.

We prefer bead blasting due to the process’s low cost and fast turnaround time. Additionally, the process consumes little raw material, thus maintaining the specified tolerance. We advise you to let the professional handle media blasting for your mold tool projects. This is because they have the capability of achieving a matte-finished area nested against a textured pattern without any overlap.

• Laser Etching

Laser is a new type of technology that has made it possible to map any texture on curved surfaces. The process combines two forms of technology. The first is 3D computer modeling. A designer can thus take a texture map then align the result with the contours of the moldable shape. This technology uses sophisticated algorithms to preserve the design’s geometry. The second technology utilized is the 5-axis motion control. This technology assists the laser in tracking over the surface topology accurately. Additionally, it is able to access undercuts and areas hidden from plain sight.

We commonly use laser etching in the automotive field. The reason is the field has large forms of plastic products that need pattern consistency over the entire length. For instance, dashboards might require a matt finish or grainy look. Despite the process costing more when compared to the other techniques, it is definitely worth the consideration. It takes time to make the needed 3D CAD models, which reflects the final cost.

• Chemical Photoetching

The process starts with coating the tool wall with a photoresist. This chemical is light-sensitive. Then, we later project the desired pattern onto the mold tool using UV light. This step leaves a photoresist area that later gets washed away, leaving a film mask behind. Later we place the mold in an acid bath, etching away the unprotected areas.

Chemical etching is cost-effective as well as fast. The process is able to produce fine textures. However, chemical etching doesn’t work well on undercuts and geometrically distorted curved surface areas. Contact Creatingway now for all your mold tooling services.

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