Over Molding

Over mold & Over molidng

Over-mold injection molding is the same as insert-molding, where an existing component is loaded into a mold and plastic is molded around it to create a multi-material single part. Insert-molding is most synonymous with combining metal components with plastic in such products as electrical pin connectors. When the term over-molding is used, the metal component is simply replaced with a previously molded plastic part. Single-shot injection molding machines are used to produce both the plastic component and the over-molded plastic. Tooling for injection over-mold injection molding requires two molds; one for the plastic component and one for the over-mold. Over-mold injection molding requires labor to handle the plastic component and load it into the second mold. Over-molding is generally reserved for higher priced parts that can absorb higher machine time and labor costs.

If you are planning to go into a plastic molding business, you should first know the different processes. Choose from a plastic molding process that fits your budget, your expertise, and your resources. In Injection Molding, melted plastic is forced into a mold cavity. Once cooled, the mold can be removed. This plastic molding process is commonly used in mass-production or prototyping of a product. Injection molding machines were made in the 1930’s. This can be used to mass produce toys, kitchen utensils, bottle caps, and cell phone stands to name a few. Plastic molding is a very technical process. It needs experts in this type of manufacturing business for it to be competitive in the market. Therefore, a very scientific and systematic study should be first made before going into this endeavor.

Injection molding is an effective way to make custom parts. Granules of plastic are melted down and then injected into a metal mold; there the molten plastic hardens into a designated shape. Then you open the mold and a new part is removed, inspected and is ready to go. Injection molding is an incredibly versatile form of molding plastics. As with everything, injection molding has its ups and down so it is important that the ends justify the means for your project needs. There are three main components in the injection molding process. The injection apparatus itself which melts and then transmits the plastic, the mold, which is custom designed, and clamping to provide controlled pressure.

Thermoplastic injection molding is molding the most widely used of all plastic processing methods. The injection molding machine reduces pelletized raw material and colorants into a hot liquid. This “melt” is forced into a cooled mold under tremendous pressure. After the material solidifies, the mold is unclamped and a finished part is ejected. Injection molding offers the lowest piece prices available, but tooling prices are generally the highest. Thermoset injection molding is similar to thermoplastic injection molding except that uncured thermoset resins are mixed, injected, and held in the mold until cured. As with thermoplastic molding, the price per piece can be low, but the tooling prices are generally very high.

Purchasing the box, some assorted socket rails, and some additional clips for the socket rails, I took the box home with me to see how well it would stand up as a replacement. The box is quite simple in construction. It’s a plastic injection molded case made of a very thick plastic. The case consists of a flip open lid (with two latches that are padlock compatible) covering a deep top storage area, and three drawers that are very similar to the large rolling tool chests that many professionals and advanced amateur home mechanics have in their garages. When you flip the lid open, the lid will immediately release the latching mechanism for the three drawers. Unfortunately, the lid does not contain any hinges or tethering that prevent it from flopping open and hitting itself on the back of the tool box. This was my only gripe involving the tool box.

Electrical Discharge Machining And Mold Making

   The use of electrical discharge machining is so essential that it is almost impossible to imagine a modern shop without an EDM machine. Many of today’s products simply could not be produced without it. Think of all the cell phones, calculators, IPods, cameras, medical devices and the endless amounts of high tech equipment that are made out of plastic!

Besides the essential role it plays in plastic injection mold making, EDM is used for the precision machining of medical parts, aerospace parts, and other highly specialized products. Electrical discharge machining, including Wire EDM, has also completely changed the way molds are made, as well as other specialized parts.

This is your information source for the EDM die sinker

Graphite  Copper EDM Tooling EDM Oil
EDM Filters Specialty Electrodes Carbide EDMing Surface Finishes

Check out the pages dealing with graphite, graphite dust, copper, dielectric fluid, electrode holders, and machinery.

What about jobs in EDM?

Find out what kind of personality it takes to have electrical discharge machining as a career job. See what the future holds in this high-tech profession.

You can also find educational material that attempts to explain this rather mysterious process. Not so long ago, it was as much black art as science. Today, however, much of the mystery is removed due to CNC controls.

Most shops send their operators to classes put on by the manufacturer of their EDM machine. It is foolish to invest so much money in a machine and skimp on the training! But it happens all the time.

What about EDM and stress?

EDM is quite a stressful occupation, to put it mildly. It may not appear difficult, but the stress levels can be exhausting. Nearly every mold component that is EDM’d is in the final stages of manufacturing. The slightest mistake can become very costly, very quickly.

There is nothing quite like the feeling of coming to work in the morning and seeing your supervisor leaning over the EDM machine staring at your workpiece. Then you find out that you had mixed up two locations and the completely finished cavity block is now completely useless!