SHOULD I USE A METAL FABRICATION SHOP TO MAKE MY PLASTIC PARTS?

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Engineers and buyers often turn to metalworking companies to produce machined plastic parts. They assume that the metal fabricator uses the same processes as a tiefziehen von Kunststoffteilen plastic fabricator and so there is no significant difference. In reality, the two companies are worlds apart. This article provides an overview of the three main reasons why a company that works with metal should not be used to produce plastic parts.

Cutting fluids for each material are crucial:
Equipment used to cut metal—even if used only occasionally for metal—can contaminate parts with oil-based cutting fluids. Many plastics are also very sensitive to petroleum based cutting fluids and will degrade when in contact with these fluids. In addition, many plastics are hygroscopic and absorb the cutting oils. If the parts are made for FDA-approved purposes or medical applications, they don’t meet the standards.

Metal splinters contaminate plastic parts:
It is difficult to adequately clean a machine that has worked with metals, especially one that has worked with stainless steel. This can lead to another contamination problem. With soft plastic material, residual metal splinters can nest in the parts.

Metal shops are experts in metal, not plastic:
Metalworking companies rarely have in-depth knowledge of plastic materials, or more specifically what material to use in an application. Plastics fabricators know which plastics are best for which function and can produce the part you need without the trial and error processes that a metal fabricator would use. A good plastics machining company will have the material knowledge and proper machining processes to consistently provide you with the highest quality parts.

Engineered Plastic Products Corporation is the leading supplier of plastic parts. EPP Corp has extensive experience manufacturing critical parts for the aerospace, military, fluid handling, instrumentation and medical industries. Capabilities include: custom plastic milling, custom plastic turning, custom plastic screw machining, custom plastic manifolds and assembly.

5 methods of joining plastic parts together

Manufacturing plastic parts is one of the most efficient ways to design and manufacture parts. In many cases today it is necessary to join two or more plastic parts together. Luckily, there are a variety of ways you can do this. I want to show you five of the best ways to do it like the pros and not the other guys.

Before we discuss the exact methods, you need some information about what you are trying to achieve. Why is that important? To choose the best method of joining two parts, you need to know exactly why the parts need to be joined. Depending on your design needs, there is a big difference in how the part should fit together. Here are some examples of things to consider on your requirements list.

  • Are the parts connected permanently or temporarily (example: a door for batteries
  • How often do the parts need to be separated (if not permanent)
  • How much dust resistance and/or waterproofing , if any, is required?
  • Will the product be used where it touches sensitive areas of the human body? (medical instruments, toys or eating utensils)
  • Will the part be subjected to heating and cooling? (like in a car parked outside)
  • How much time does it take to assemble the parts?
  • Are the parts assembled by machine?

Make a list of your requirements that will help you figure out the best way to figure out how to go about it. Now let’s move on to some solutions.

Using screws is a very common way of assembling plastic parts. The advantages are that anyone who can turn a screw can assemble the parts. Screws can be used to connect plastic parts to various materials such as metals and composites. This is also easy for smaller volumes. A downside, however, is that as the number of parts increases, it takes more time, money, and labor. Assembly work or expensive machines are required for large quantities. Screws allow disassembly, but will wear out the screw bag if the product is disassembled frequently. The screw is locked with some glue.

General practice

The common practice is to have the hole formed on a part for the screw to go through. The part to be connected to the first has a pilot hole. The pilot hole is smaller than the screw threads. When the screw is first driven into the pilot hole, it cuts into it. This gives a strong connection for the screw to clamp both parts together. Using a metal insert can increase the strength of the connection and allow for more frequent disassembly.

Typically, use screws with thick heads, such as pan-head or button-head screws. Pan head screws should not be used as the conical head will overstress the plastic. Be careful when connecting rubber parts with screws.

One of the most popular ways to connect two pieces of plastic is to use hooks. A hook, sometimes called a snap, looks like a barb on a fishing hook. This hook snaps into a slot in the part to be connected. A hook can be set up for either a permanent or temporary connection.

Shaped like a fish hook

If the hook is shaped like a fishhook with a very sharp barb and the slot is not accessible, this is ideal for a permanent connection. Toys and small appliances often use this attachment method.

If you want a detachable joint, such as a battery cover, the hook should not have a back angle to act more like a detent. A latch is better when the parts need to be removed and reassembled. A good example of this is a Fastex buckle, which you can find here. You’ve probably seen these on luggage, child seats and outdoor gear.

Adhesives can also be used to easily connect parts. Adhesives like epoxy are not only useful for bonding plastics, but can also be used to bond plastics to metal, composite, or ceramics. With proper selection, the joint can also seal out water, dust, and other contaminants. Because every adhesive is different, follow the adhesive manufacturer’s directions and warnings. You should consider using adhesives as permanent.

Select Adhesives

Be careful when choosing adhesives if the product will be tiefziehen von Kunststoffteilen exposed to regular cycles of hot and cold temperatures. Depending on the conditions the product will be exposed to, some adhesives may be a better choice. Be careful what materials you are gluing and make sure the glue works with all the parts you are gluing. Special care should be taken with adhesives when the parts they are used on will come into contact with sensitive parts of the body.