What is precision injection molding?
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Creates precise plastic components
Materials should have a low shrinkage capacity
Rely on the precision injection mold
A slow and steady process
Uses polymer optics
Many molding processes are known to mass produce products that are used in daily life. However, various industries have parts and pieces that are too complex to be made with ordinary plastic injection moldings. A process called precision injection molding is used for such processes.
But, what is precision injection molding? It is a highly technical process that makes use of precise molds. It is not used to develop whole products, instead, it develops more complex plastic parts.
It differs from convection modeling in many ways, from the materials used to the mold created to the machine used in creating the product. This article tackles all you need to know about this technical process. By the end, you can assess if this is the molding process that you need for your next project.
Creates precise plastic components
Compared to plastic injection molding, this method produces precise plastic parts. It does not mass produce whole parts. These products that are made in the process replace high-precision metal parts from different industrial appliances.
The plastic components produced in precision injection molding require a tight tolerance. That means that the requirements for the product have precise and accurate procedures. When not followed, it can break inside the mold.
Products that are produced in precise injection molding are also comprised of complex geometric parts. These items have specific shapes that are needed for certain items in automotive, pharmaceutical, information technology, and medical fields.
Materials should have a low shrinkage capacity
Precise injection molding can cause plastics to shrink during the manufacturing process. That&#;s why its materials are different from other injection molding materials.
When materials have a high shrinkage capacity, they melt as they undergo the precise injection molding process. It ruins the product in the end.
The materials used for this molding process need to have a low shrinkage capacity. The shrinkage required is around +/-0.01&#; or +/-0.02&#;. However, many materials can&#;t reach this range.
An example of this would be ABS, a thermoplastic polymer. This kind of plastic can retain its elasticity while going through high temperatures. However, its shrinkage of +/-0.06 is still not appropriate for precision molding. Glass and other resin can be added to reach the desired shrinkage. These help the material absorb the excess heat while keeping the plastic stable.
Rely on the precision injection mold
The precision made during this molding process is achieved through its mold. It needs to suit the design engineering requirements.
To craft the mold, it needs to undergo accurate study, design, and testing. Many elements need to be taken into account for the mold. Here are some of the elements that need attention:
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The mold cavity size &#; its position and the number of cavities it has
The precision of the parting surface
The materials used for the mold (this can be made from steel alloys or cast irons)
The bottom plate&#;s thickness
The runner size
Precision injection models are made with tolerances between +/-0.02&#; and +/-0.01&#; or less. All elements mentioned are considered when considering the dimensions tolerance.
A slow and steady process
A high-precision model is required when creating plastic parts that have tight tolerances. Each part made in a precise injection model needs to be identical. This process can only be applied to plastic parts that are placed and connected with other parts in a fixed form.
Because of the precise products, the manufacturer should not rely on rapid tools for this method. Precise injection modeling is a slow and steady process that makes a high-precision tool.
Uses polymer optics
Polymer optics are used in precise injection molding. This is when CNC machining is used to mold the plastics into precise and calculated shapes. The machines have high pressure that helps improve the quality and precision of the plastic parts. They also manage to repeatedly create an accurate product.
The entire process is automated and conducted through computers through an automatic handling system. It allows the producer to customize the process for the product needed to be molded.
This reduces the cost of labor while increasing production efficiency thanks to its automated process.
Key Takeaway
Now that you&#;ve answered what precision injection molding is, you can check if you can apply it to some of your products. As stated above, it can also develop a wide variety of complex products.
Sometimes we get CAD files that were translated from .STL files. While .STL files are acceptable for 3D printing, they create problems with molded parts. That&#;s because they reveal the part&#;s surface as a series of triangles, rather than the true curves you would find on real parts.
The bottom line is that we will be unable to quote these designs and send them back requesting changes, which costs you time.
Instead, output your designs as STEP files using CAD software such as SOLIDWORKS, Inventor, Pro-E, Catia, or any number of others and define thicknesses clearly, then you&#;ll be good to go.
Building radii into a part can be a hit and miss proposition. Only use them in necessary areas, for example, to eliminate sharp edges that an end user may touch, or in critical functional areas such as a lead-in to an assembly.
Some radii are used on inside corners of critical features to make more robust geometry. Inside radii can also help on material flow patterns. In general, proper placement of corner radii can create stronger molded parts.
Parting lines always make for interesting design and manufacturing challenges. Typically, we want them to be as unnoticeable as possible, and deciding where to locate them is an exercise filled with aesthetic and mechanical considerations. But watch out. If you try putting a fillet or radius around a parting line, you might end up with undesirable minor undercuts in your mold and maybe even flash.
Undercuts are features that make it difficult to eject a part from its mold. Sometimes these are created using techniques such as side-action cams or pick-out inserts, but these add manufacturing time due to molding costs and complexity. If it&#;s possible to eliminate undercuts, it will definitely speed up manufacturing time.
For more precision mold partsinformation, please contact us. We will provide professional answers.