Cold Runner Molds
Cold runner molds are good examples of more traditional tooling in that they utilize sprues and runners to gate into the part. This is typically the least complicated form, however may result in larger amounts of wasted material and slower running cycles. Depending on the application, a percentage of wasted material may be re-ground and re-processed for future use, though this could affect the physical properties of the resin.
Dealing with more advanced, high-cost materials such as engineering and medical grade resins or the inability to use regrind in your application may lend itself to using a more efficient hot runner mold for your project.