| Guide pins and guide bushes | Pin diameter, straightness, and alignment with the bush | Example ground-diameter tolerance: ±0.005–0.010 mm | Helps the mold halves close repeatedly in the intended position, reducing mismatch at the parting line and uneven wear. | Micrometer or air gauge for diameter; dial indicator or coordinate measuring machine (CMM) for alignment. |
| Locating pins and bushings | Position and fit between mating plates or inserts | Position tolerance set on the drawing; a precision application may specify ±0.010 mm | Maintains the location of mold plates and interchangeable inserts during assembly and repeated production cycles. | CMM measurement of pin and bore positions; fit checked against the specified drawing dimensions. |
| Cavity and core inserts | Profile, critical dimensions, and surface finish | Example critical-dimension tolerance: ±0.010–0.025 mm | Controls the geometry transferred to the molded or formed part. Accurate insert dimensions support consistent part size and shape. | CMM or optical measurement for profile and dimensions; surface roughness tester where finish is specified. |
| Ejector pins | Pin diameter, straightness, and alignment with the ejector bore | Fit and clearance specified for the application; pin diameter may be controlled to ±0.005–0.010 mm | Promotes consistent movement and helps reduce sticking, pin drag, and unwanted marks on the ejected part. | Micrometer for diameter; runout or straightness check; functional movement check in the assembled plate. |
| Slides, lifters, and wear plates | Guide-face parallelism, clearance, and contact surfaces | Clearance and parallelism defined by the design; example parallelism target: 0.010–0.020 mm | Supports controlled side-action movement and repeatable shutoff, helping prevent flash and dimensional variation around moving features. | Dial indicator, feeler gauges, surface plate inspection, and assembled-motion check. |
| Sprue bushings and locating rings | Concentricity and alignment with the machine nozzle | Concentricity target specified by the mold and machine interface drawing | Helps align the material-entry path, reducing the risk of nozzle misalignment, leakage, and uneven filling. | CMM or concentricity gauge; interface dimensions checked against the machine and mold drawings. |
| Cooling-channel components and seals | Channel position, bore size, and sealing-face condition | Channel location tolerance defined by the cooling layout; pressure test performed to the project specification | Accurate channel placement supports more predictable cooling. Properly fitted seals help prevent coolant leakage into the mold. | Dimensional inspection of accessible features; leak or pressure test using the specified test pressure and duration. |
| Note: The numerical values above are illustrative engineering targets, not universal standards or guaranteed component specifications. Required tolerances depend on the mold design, material, operating conditions, and part requirements; the approved drawing and inspection plan take precedence. |