Mold Factory Inspection Checklist: Key Equipment to Check On-site
Mold processing quality, delivery schedule and dimensional stability largely depend on the factory’s in-house processing, testing and maintenance equipment. Many mold projects suffer from dimensional deviation, surface defects and delivery delays because buyers only check finished samples without verifying supporting equipment. Heavy reliance on outsourced processes lengthens quality control chains and raises risks. During on-site factory visits, inspect equipment by processing sequence, confirm precision grade and running status, and review maintenance and calibration records to avoid factories displaying idle equipment without stable processing capacity.
CNC Machining Centers (High Priority)
Classify ordinary CNC, high-speed CNC and graphite CNC. Check whether the travel range matches your mold outer size, machine brand, production year and spindle speed. High-speed machines are used for hard steel finish milling and pre-polishing, suitable for precision housing, connector and lamp molds. Check running cavities and cores, and inspect guide rails and ball screws for oil leakage and crash marks. Request regular precision calibration records. Graphite CNC must be placed in independent dust-proof zones to avoid graphite powder contaminating other machines. Confirm whether large molds, deep cavities and hard steel machining are finished in-house or outsourced.
Electrical Discharge Machines (EDM)
Include standard EDM, mirror EDM and double-head EDM. Mirror EDM directly determines surface quality for high-gloss and transparent parts such as RHCM, PC optical and thin-wall precision molds. Check electrode libraries and automatic electrode change functions, and observe deep ribs, narrow slots and sharp corners being processed. Dirty oil tanks with heavy sediment will destabilize discharge. A separate dust-free EDM area reduces surface pits caused by impurities.
Wire EDM (WEDM)
Prioritize slow wire EDM. Medium wire EDM is only acceptable for simple structural parts. Slow wire EDM produces inserts, angled lifters, precision sliders, micro holes and tiny connector features with superior accuracy and surface finish. Check automatic wire threading and finished cutting surface quality. Many small factories outsource all slow wire work, which brings unstable tolerance and delivery risk. Drilling machines are matched for pre-drilling wire entry holes.
Grinding Equipment
Surface grinders, jig grinders and optical profile grinders are included. Surface grinders guarantee flatness of mold bases, inserts and parting surfaces. Jig grinders are essential for precision holes and tiny locating holes required by medical and connector molds. Check worktables, magnetic chucks for scratches, and verify proper wheel management and clean cooling systems.
Testing Equipment (Determines Mold Consistency)
CMM coordinate measuring machines are the most important testing equipment, used to inspect 3D dimensions and position tolerance of cavities and cores. 2.5D vision measuring machines and tool microscopes test micro holes, thin walls and narrow slots. Height gauges, micrometers and gauge blocks are standard auxiliary tools. Confirm CMM calibration validity and constant-temperature room environment, and ask for test reports of existing molds. Blue light scanners are used to compare molded parts against 3D models to detect dimensional deviation.
Mold Closing Machine and Molding Auxiliary Equipment
Mold closing machines are used for fitting and checking parting line sealing and shut-off features without using an injection machine. Poor fitting quality is common for factories without this equipment. Check injection molding machines, confirm tonnage range covers your mold locking requirement, and check for two-color and all-electric machines. Supporting temperature control units include water mold temperature controllers, oil heaters, chillers and dehumidifying dryers. PC, PA, PET and TPE molding require stable temperature control, and high-gloss molds need high-temperature mold temperature machines.
Auxiliary Tooling Equipment
Radial drills, tapping machines, band saws, grinding machines and polishing stations. Independent polishing zones are equipped with sandpaper, diamond paste and ultrasonic cleaning tanks. Overhead cranes with proper lifting capacity and mold storage racks are required for large molds. Hot runner test benches are mandatory for hot runner molds, to test heating coils and thermocouples before mold trial.
Additional Soft Information to Confirm
Record which processes are outsourced, such as CNC, slow wire, polishing and heat treatment. More outsourced steps mean higher risk. Check maintenance logs and precision check records. Old machines with frequent crashes and no maintenance cannot guarantee stable precision even from famous brands. Heat treatment is a major source of mold deformation; confirm long-term cooperative heat treatment suppliers with material certificates. Check equipment utilization: heavily dust-covered idle machines are rarely used for precision mold orders.
Quick Risk Warning Points
Factories listing equipment that cannot be found on site; precision projects only with medium wire EDM and no slow wire; mirror requirement without mirror EDM; CMM placed outside constant-temperature room or seldom used; no mold closing machine and all fitting work done on injection machines.
