Plastic Injection Molding Service
Injection molding machine
If you need online injection molding we are one of the most capable and affordable sources and we can get the job done right. Download our Free CAD software today and design your custom part or convert an existing file. Order online for ultimate speed and convenience.
About our service
eMachineShop offers a unique approach to providing custom injection molding services. We provide special free CAD software that allows you to easily draw your part or convert an existing design. The software then provides instant expert feedback about your design and helps you correct any issues to ensure a smooth trouble-free process. It then gives an instant price - saving you from waiting for quotations. And finally the software allows you to order your custom parts online with just a click - at prototype or production quantities.
We stock a wide variety of materials, use state-of-the-art machines and diligently follow all design specifications. We continually strive to improve and optimize our processes and maximize customer convenience. Our customers range from inventors to businesses to government agencies. We are focused on quality and customer service.
Get started today - design, price and order your custom parts through eMachineShop.
How plastic injection molding works
Injection molding produces parts by forcing molten plastic into a mold where it cools and hardens. Granular plastic is fed by gravity from a hopper into a heated barrel. As the granules are moved forward by a screw-type plunger, the plastic is forced into a heating chamber, where it is melted. As the plunger advances further, the melted plastic is forced through a nozzle into the mold cavity. The mold remains relatively cold so the plastic solidifies almost as soon as the mold is filled. Custom steel tooling is required and adds to the initial cost but is quickly amortized.
Injection molding provides low cost at moderate to large quantities. This method of making plastic parts is an extremely versatile process for producing a wide range of parts with an excellent finish. Almost any 2D or 3D shape can be achieved. However draft is required in most cases as the shape must allow ejection from the mold. Side holes and even threaded holes are possible though they complicate the tooling.
Types of parts
Examples of parts made by molding include: Gears, Enclosures, Brackets, Robot Parts, Washers, Front Panels, Motorcycle Parts, Auto Parts, Toy Parts, Knobs, Pulleys, packaging, appliance parts, power tool components, electronic enclosures and valves.
The following materials are some of the ones commonly molded: Nylon, Acetal, Polycarbonate, Polystyrene, Acrylic, PTFE, ABS, PVC.
Cost reduction options include:
- Minimizing size of part
- Minimizing material volume
- Minimizing side holes and recesses
- Arranging multiple pieces in one mold by connecting them with small
bars ~0.1", however the sub-components must not have widely varying
- Minimizing side features and threaded holes
- Using living hinges
The following terms are commonly used for this manufacturing process:
- Ejection pins are rods that push the part out of the mold.
- The gate is the
location where plastic is injected.
- The parting line is the location where
the two mold halves meet - a thin line will appear at this location.
- A living hinge is a thin connection provided between two sections of a
molded part so that it can be used as a hinge, e.g. a box, with a lid,
molded as one piece.
- Insert molding is where a rigid part is inserted into the cavity prior to injection - a screw driver with a plastic
handle is an example of insert molding.