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Plastics Injection Molding - pti injection molding

Author:gly    Date: 2024-10-15    

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Injection molding Delrin is suitable for larger parts and is more reliable than 3D printing. POM pellets (either Delrin or acetal copolymers) for IM are also more widely available than Delrin 3D printer filament. However, the semi-crystalline nature of Delrin can increase shrinkage of molded parts.

Delrin is a popular engineering thermoplastic for CNC machining, both because of its material properties and its machinability. Its main advantages are:

Design is one of the most important factors in avoiding part defects. Avoid mistakes that can be costly both in regard to time and budget later on.

Delrin machining has some limitations that make it unsuitable for certain parts and applications. Its main limitations and weaknesses are:

Calculating shot volume to make sure your barrel has enough capacity can be accomplished by working with your injection molder to run a mold flow analysis. On some engineered materials, the increased residence of the material in the barrel can cause the material to degrade, resulting in poor part quality. Mold flow analysis will help you determine the volume of your part and runner while determining any factors that would cause safety issues.

Are you a product designer or engineer that is looking for more information on how to make your plastic part design more efficient in regard to cost and production time? One important consideration during the part design process is to have a good understanding of plastic injection press basics including the size of machine needed for your part.

Delrin parts for electronics applications include insulators, connectors, bobbins, connectors, and consumer electronics parts like keyboard covers.

Specialize in CNC machining, 3D printing, urethane casting, rapid tooling, injection molding, metal casting, sheet metal and extrusion

Delrin is suitable for machining processes like milling and turning, and is supplied in sheets or extruded bars for this purpose. The material can also be cut with a laser cutter, and its granulated form is used for injection molding and plastic extrusion.

Also known as acetal, polyacetal, or polyformaldehyde, its most widely recognized brand name is Delrin, which is made by chemicals company DuPont. (Other brand names for POM include Kocetal, Ultraform, and Celcon.) Note that Delrin is an acetal homopolymer, but POM can also be made into a copolymer.

Delrin mechanical parts can include gears, housings, springs, fan wheels, valves, bearings, rollers, and scraper blades.

Delrin is widely considered to be one of the most machining-friendly plastics, so it does not require any drastic precautionary measures. That being said, it responds better to certain design considerations and machining approaches than others.

In general, if the desired geometry and dimensions of the Delrin part are machinable, then machining is the best option of the three.

The most successful parts are created when there is constant communication between a part designer, tool designer and manufacturer.

When determining press size for your plastic part, it’s important to calculate the total projected shut-off area. This area consists of only the space that is 90 degrees to the direction of the injection molding machine platens. Thickness does not have any implication on the clamp tonnage and the general rule is to have 2 to 5 ton of clamp tonnage per square inch of projected area.

Although intrinsically opaque, Delrin is available in all colors. It has a density of 1.410–1.420 g/cm3 and offers rigidity to -40°C. It is 75–85% crystalline with a melting point of 175°C.

Additionally, smaller presses have tie bar spacing too narrow to accommodate larger products. If the mold doesn’t fit between them horizontally or vertically, you must move up in press size. Many injection molders offer press sizes ranging from 68 tons up to 400 tons.

Regular injection mold maintenance can help your mold last longer, run with less interruptions & will ultimately save you time, money & frustration.

Designing a plastic part for manufacturability from the outset involves several considerations that can have a significant impact on key variables

In order to streamline your process, consider these questions before requesting an accurate quote for your part design, development and production.

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Your plastic injection molder should help you determine the size of the machine needed to help you achieve the best result for your product. Knowing an approximate size of what will be needed can help you determine the best injection molding partner based on the press capacity they have available. For example, larger presses cannot accommodate smaller molds because they can’t close far enough and the injection process will not work.

Having a general understanding of how to calculate press size is a good first step in determining what injection molding partners are available to you. Strong partners will make recommendations on how to appropriately tweak your part to ensure the final design fits your manufacturing needs and reduces upfront tooling costs. Nicolet Plastics has press sizes up to 610 tons.

Delrin is a versatile CNC machining material and is not limited to machining project. Delrin 3D printing filament can be used to make 3D printed Delrin parts, and Delrin injection molding is also possible.

Consistent quality parts start with a quality, well-made and maintained mold. What expectations should you have for the care of your investment?

Polyoxymethylene (POM) is a semi-crystalline engineering thermoplastic characterized by its stiffness, excellent dimensional stability, hardness, and strength.

This article goes over the basics of machining Delrin: what Delrin is, the benefits of machining Delrin, the limitations of machining Delrin, common applications of machining Delrin, and tips for designing and machining Delrin parts.

3ERP is a leading provider of plastic CNC machining services with expertise in Delrin machining. Contact us for a free quote on your next Delrin prototypes or Delrin parts.

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Pressure plays a significant role in the overall quality of a plastic part. Pressure keeps the mold closed during the injection process. Too much or too little pressure can cause various issues such as flashing and viscosity. One important consideration in regard to pressure is that plastic compounds react differently from one another based on their Melt Flow Index (MFI). MFI measures the ease of flow of a thermoplastic polymer and the higher the MFI, the higher pressure needed to create a successful part.

“Bigger the better” is not always the case when determining the press size needed. In the molding process, plastic is injected into the mold at an exceptionally high-pressure rate, which creates a natural pull to force the mold open. A press is designed to keep the mold shut with larger parts requiring more tonnage and force, and smaller parts requiring less. A general calculation for determining press size needed is as follows:

“Safety factor” is an additional percentage added to your calculation as a buffer to help reduce defects in your part. Most injection molders will recommend 2.5 times the surface square inches of the part and an additional 10% as a safety factor. If you have a part that is 120 square inches, you would need a press size with 300 tons of pressure. When you add the 10% safety factor, the required press size would have 330 tons of clamping force.

From cars to consumer electronics to kitchenware, Delrin is just about everywhere: the high-strength thermoplastic makes great consumer products and is favored by machinists for its good material properties and high machinability.

3D printing Delrin offers geometrical flexibility and is suitable for a very wide range of prototyping applications, but its limitations include poor print bed adhesion, possible delamination, and a limited temperature range.

Machined Delrin parts can be found everywhere, from the automotive industry to consumer electronics. Some common Delrin machining applications include:

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