Mould Assembly

Mold assembly is one of the most critical steps of mold making procedure, all the parts machined or purchased need to be put together and required to be work functionality. Mold assembly job requires comprehensive understanding of mold structure as well as injection molding. Quality of mold assembly determines the mold precision, injection productivity. The work instructions below can be treated as a guide for mold makers.

All parts are machined correctly and clean, the work tools required are available and the workplace is well organized, before assembling the mold, all the components must be checked and verified.

Make sure all surfaces are polished accordingly, especially the deep rib – it could cause serious de-molding problems if it was not polished properly. Check all sharp edges of cavity and cores, all sharp edges that have no function requirement must be broken 0.01 radius. Verify that the mold gate and runner size is correct according to design; make sure the runner is polished. The mold base should have correct markings, pay bar slots between the parting line, clamp plates, support plates and ejector plates, check if lifting holes for each plate is available and mark with correct thread dimension, and the lifter bar as well. Check if the sprue and nozzle are in correct size, check if the location ring is correct.

Check if the knock out holes dimension, layout and clamping slot is correct. Check if the part surfaces, deep ribs, sliders, pins, end of mold flow are all properly vented. All pins, cores, sleeves must be marked for correct location, check the dimension and fitting clearance include length and head. Assure that ID is engraved on cavities on multi-cavity molds, verify that part number is engraved. Verify that all moving parts, such as ejector blades, slides, lift cores, etc. are of dissimilar material or nitrided to prevent galling. Ensure the water line is through, marked in and out correctly, make sure the water line tube will not interfere with clamp slots.

Move the ejector plate back and forth to verify that it moves freely. Push the ejector plate forward and check if all pins, sleeves, lift cores and all other moving components spin freely. With ejector plate forward, push ejector blades, sleeves, lift cores and all other moving components in and out to verify correct clearance. Open and close mold on bench in an injection molding machine sequence to verify that the early return system functions properly. Check if slides clear ejector pins, lift cores and any other moving parts with sufficient clearance.

And there are more for different types of mold structure, such as 3 plate mold, they have unique design of latch lock, limited pull plate, runner plate etc. and for hot runner molds, they have special design for hot runner manifold plate, and installation of hot nozzle wiring, plugging etc.