Mold design is the start of any successful mold-making project, so a careful evaluation and optimization process is very much necessary, review the design to verify the plastic parts requirements and mold manufacturability are all satisfied.
Plastic Parts Related
- Is there a “parts to customer” promised date?
- Has the mold completion date been established?
- Has the cavity level been established?
- Has the mold cost quote been completed?
- Has the cycle time been established?
- Has the material to be molded been determined?
- Is existing product available?
- If 7 is yes, should the existing gate location be used?
- If 7 is yes, is the product symmetrical in design?
- Are maintenance costs built into the price?
- If there is existing product running, is it running under deviation?
- Are there gages available for this product line?
- If there are no gages available, will they be available when the construction is completed?
- Given the proposed cavity level, will the product fit into one of the three standard size modules?
- Is the shrinkage data available at this time?
- Is there an existing or similar product for which reliable shrink data is available?
- Should the tool be designed for “steel safe?”
- Has a product polarization feature been identified?
- Are Pro E models available?
- What level of tooling supports the business?
- Can the part date code (clock code), if applicable, be changed without removing the mold from the press?
Cavity
- Are slender inserts protected from injection molding pressure?
- Are sliding areas made of dissimilar steel, hardness or coatings?
- Is stationary-half ejection necessary?
- Is cavity construction strong enough to prevent deformation due to clamp pressure?
- Should core pins be piloted?
- Is mismatch needed to maintain critical dimensions?
- Do cavity blocks have benching pins?
- Are fragile areas of cavity inserted?
- Are cavity inserts backed up by hardened steel?
- Proper steel type specified for various components?
- Proper plating(s) specified?
- Proper polish(es) and draw polish specified on tool drawings?
- Is gate area inserted?
- Has cavity been properly vented?
- Do vents reach atmosphere or vacuum?
- Has cavity been evaluated for ease of maintenance?
- Has gate puller been provided for a gate in moveable half?
- Is draft present for telescoping tooling?
- Is sufficient draft present for a side release and part ejection?
- Is cavity sequence definition necessary?
- Has computer analysis been done for runner sizes?
- Is any steel telescoping less than 3 degrees?
- If steel is telescoping less than 3 degrees, can this be increased?
- Is strip action required on A side?
- Is strip action required on B side?
- Do internal detentes require either half core to float out prior to ejection?
- Have “key features” been identified?
- Does the “key feature” dimension correlate with the area of the product most functionally critical and that will be most affected by process changes?
- Are ejector pins located at intersection of runners?
- Have runner cold-slug wells been vented?
- Will the runner stay on the ejector side of the mold frame?
- Is the sprue bushing retained in the mold frame?
- Will the nozzle area of sprue bushing trap material?
- Is an ejector pin properly located to eject the gate?
- Has sprue length and diameter been minimized?
- Does cavity need alignment feature to protect steel (for cavities without frames)?
- Have complete parts lists been drawn?
- Are all drawings properly numbered?
- Are set-up sheets prepared for multiple part numbers?
- Are interchangeable inserts polarized?
- Was any texture requested?
- Any special requests made by Manufacturing Department?
- Was vacuum requested for vents (end of fill or full vacuum depending on product)?
- Are enough ejector pins present for short shots?
- Were “pull grooves” requested or needed?
- Cavity identification called out on the tool drawings?
- Circuit identification called out on the tool drawings
- Proper company logo called out on the tool drawings?
- Broken corners to be shown only to aid in handling/shut off clearance.
- Is the polymer material code engraved in the cavity?
- Are the runners vented?
- Do units stand proud from frame for shut-off?
- Has a hot sprue been considered?
- Are there separate jack screw holes for face-mounted units?
- Has product been reviewed for max core out of material?
- Are wedge locks installed?
Ejector System
- Is ejector travel greater than length required for part and runner ejection?
- Are stop pins provided to limit ejector travel?
- Is frame travel limited to less than cavity travel on face mounted cavity units?
- Are ejector pins, support pillars or ejector sleeves not interfering with knockout holes?
- Is strength of ejector plate compromised by use of support pillars?
- Will hand-loaded inserts stay on their locator pins at top of full ejection stroke?
- Is ejector system guided on class 1 and precision molds?
- Can the ejector plates be pulsated to flick plastic parts off of the ejector pins?
- Is an “early return” system required?
- Do compression springs use an operating range (25-35% of free length)?
- Are “cushioned” return pins required when ejector pins are on a clamping parting-line surface of cavity?
- Are stripper plates of adequate thickness?
- Have additional screws and stop buttons been added to ejector plate sets on larger die casts?
- Is a hydraulic return required?
- Are safety limit switches installed on die cast having ejector devices inside of slide paths?
- Are springs required to return ejector plates?
- Can ejector plates be tied in to the press?
- Are cold slugs 2 times the runner diameters?
- On sub-gated parts, is the ejector pin located for proper gate ejection/runner flex?
- Do all runner intersections have a radius?
Temperature Control System
- Has mold cooling analysis been done?
- Are frame and cavity designed for pulse cooling?
- Are cooling line connectors recessed?
- Will fitting locations interfere with tie-bars or clamps?
- Are fittings that extend beyond exterior of mold frame protected from damage?
- Is there a 3/16″ min. wall surrounding cooling lines?
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Are there sufficient cooling lines in the following areas:
- “A” plate?
- “B” plate?
- Stripper plate?
- Three-plate runner plate?
- Back-up plate?
- Sprue and runner area?
- Are all water connections marked “In” or “Out?”
- Are all air cooling connections marked “In” or “Out?”
- Are all vacuum connections marked “Vacuum?”
- Are cooling lines needed in cavity?
- Should “in” or “Out” locations be staggered from injection mold plate to injection mold plate?
- Are the mold plates slotted for quick-change cavity cooling connections?
- Should waterlines be nickel plated?
- Was a Staubli water connector requested?
- Would air cooling benefit any cavity areas?
- Is mold to be heated or cooled?
Slides
- Is slide travel adequate to clear part?
- Is a positive slide lock designed in the tool?
- Are there wear plates under the slide?
- Are there wear plates in the lock blocks?
- Are limit switches present in case of “slide rebound?”
- On slides wrapping around cores, is there adequate clearance between ejector devices and slide steel?
- Are there early return pins (.25″ minimum diameter) provided when ejector devices are under slide steel?
- Are slides removable without disassembling the mold frame?
- Are the slides designed with temperature control?
- Are grease grooves designed in sliding areas?
- Will the angle pin pick up the slide?
- Are slides locked against “blow back?”
- For cores passing through a slide, has proper” swelling clearance” been incorporated into the design?
