In order to ensure rationality and consistency of mold making process, optimize processing technology, and improve precision of mold making, each mold factory generally formulates process standards that suits its own mold factory. This article provides a standard for reference.

 

When craftsman has programmed craft card, processing allowance, orientation of reserved amount, roughness requirements and precautions should be specified in process card.
Principles for processing process card: Under premise of ensuring accuracy and quality, equipment with high processing efficiency is preferred. Processing efficiency of milling, CNC machines and grinding is faster than wire cutting and electric pulse, especially electrical pulse processing efficiency is the slowest. Dimensions on the drawings cannot be changed at will (only technician can change).

For workpieces requiring heat treatment process, shape of material before heat treatment needs to add 0.25mm of grinding machine margin. For mold core and part of insert need CNC roughing, allowance for single side is 0.2mm. Rough milling requires a margin of 0.3-0.5mm on one side. After wire cutting, for workpiece that needs to be grinded, molding part allowance for single side is 0.5mm, grinding allowance is 0.1mm in the shape of open side. Mirror polishing after CNC finishing and electric pulse, leaving a 0.03mm polishing allowance on one side.

Manufacturing precision of mold size should be in the range of 0.005~0.02mm; verticality should be in the range of 0.01~0.02mm; coaxiality should be in the range of 0.01~0.03mm; parallelism of upper and lower planes of moving and fixed mold parting surfaces is required to be in the range of 0.01 to 0.03 mm.
After clamping, gap between parting surfaces is smaller than overflow value of formed plastic. Parallelism of other template mating surfaces is required to be in the range of 0.01 to 0.02 mm; matching precision of fixed part is generally in the range of 0.01 to 0.02 mm; if small core does not have insertion requirement or size is small, it may take a gap of 0.01 to 0.02 mm bilaterally. Matching precision of sliding part is generally selected from H7/e6, H7/f7, and H7/g6.
Note: If there is an insert on mirror surface that is attached to step, fit should not be too tight. Otherwise, when insert is knocked from front to back, tool used for tapping is easy to break mirror surface. If it does not affect product size, it can be used with a gap of 0.01 to 0.02 mm.

Mold cavity core should first disassemble main body electrode, then disassemble other main electrode, and finally disassemble local electrode. Fixed-mold appearance electrode should consider overall processing. For place where CNC clear angle is not in place, wire cutting clear angle is adopted, so that fixed-mold appearance is complete and there are no joints. For ribs and columns with different depths of moving mold, they can be processed together on one electrode as much as possible. For deeper ribs, do inserts and electrodes separately to prevent carbon deposition during electric pulse. Movable mold electrode should not be cut clear angle by wire cutting after CNC milling. If necessary, electrode should be disassembled or directly cut by wire cutting. Spacing between ribs and ribs or columns of moving mold exceeds 35 mm, which should be done separately to save copper material.
Large electrode rough machining spark position is unilateral 0.3mm, finishing spark position is unilateral 0.15mm; general electrode rough machining spark position is unilateral 0.2mm, finishing spark position is unilateral 0.1mm; small electrode rough machining spark position is unilateral 0.15mm, and finish spark position is unilateral 0.07mm.

Mold core and insert need to reserve a margin of 0.2mm on unilateral part of the CNC rough machining. For workpieces that require CNC finishing after heat treatment, if appearance of product allows, CNC machining is preferred for mold cavity core in which CNC can be finished in place. If electrode cannot be machined in place, it is processed by electric pulse.

 

1) preparation materials;
2) Milling process: drilling water hole (distance between water hole plug and horizontal water hole is 3-4mm), threading hole, drilling, tapping screw hole, drilling, hinge pinhole, mold number, reference angle;
3) CNC machining: rough machining;
4) Heat treatment: indicate hardness requirements;
5) Grinding process: grinding six-sided square ruler, shape is fixed by frame size (if mold core is one piece, outer dimensions are 0.03mm-0.05mm lower than drawing size. If mold core is two pieces, outer dimensions of two mold cores are 0.03mm-0.05mm lower than drawing size. Part that can be formed by grinding machine must be ground and formed;
6) For mold core that needs CNC finishing, arrange CNC finishing. If mold has fonts and mold numbers, it needs lettering processing;
7) Wire cutting process: middle wire processing insert hole, inclined top hole, thimble hole, boring hole, etc.;
8) EDM: processing according to drawings and pulse instructions;
9) Polishing: Roughness and requirements of polishing are written on process card. Polished area is marked with a marker on workpiece. If there is a mirror requirement and cycle is not enough, it can be rough polished first. Then finish polished after mold trial.
10) Assembly;
11) Mold trial.

 

1) Preparation materials: Craftsman defines whether workpiece is processed in one piece or in multiple pieces according to size and shape of workpiece. If multiple pieces are processed together, craftsman needs to plan processing of workpiece;
2) Milling process: Fitter will process according to workpiece drawing or layout drawing of craftsman, drilling water hole(distance between water hole plug and horizontal water hole is 3-4mm), threading hole, drilling, tap screw hole, drilling and reaming pin hole, forming part rough, mold number, hanging table letting position;
3) CNC machining: If CNC machining is required, arrange CNC roughing;
4) Heat treatment: indicate hardness requirements;
5) Grinding process: grinding six-face square, part that can be formed by grinding machine must be ground and formed;
6) For CNC finishing workpieces, arrange CNC finishing, such as inserts with fonts and model numbers to be engraved;
7) Wire cutting process: middle wire processing insert hole, inclined top hole, thimble hole, etc.;
8) EDM: processing according to drawings and pulse instructions;
9) Polishing: Roughness and requirements of polishing are written on process card. Polished area is marked with a marker on the workpiece. If there is a mirror requirement, cycle is not enough, and mold trial can be roughed before being finely polished.
10) Assembly;
11) Mold trial.

Process 1:
1) Wire cutting process: cutting outer dimensions with middle wire, pull-tab, leave remaining amount to grinding, and forming part is rough;
2) Grinding process: grinding thickness, slope, molding;
3) Electrical discharge machining;
4) Polishing process.
Process 2:
1) Wire cutting process: middle wire cutting shape, insert hole, thimble hole, size cutting (C view), hanging table and forming place is rough;
2) Grinding process: grinding height, hanging table, slope, molding;
3) Electrical discharge machining;
4) Polishing process.

1) Wire cutting process: fast wire cutting shape, leave remaining amount to grinding(A/B view), pull-tab, leave thickness remaining amount to grinding;
2) Dimensional size grinding, grinding table, slope, molding;
3) Electrical discharge machining;
4) Polishing process.

1) Centerless grinding: fixed dimensions grinding;
2) Grinding process: clearing corner at hanging platform;
3) Wire cutting process: fast wire cutting length (single side 0.1mm grinder allowance), cutting pin hole, vent hole;
4) Grinding process: grinding length, molding.

 

1) Wire cutting process: middle wire cutting shape, head of insert surface should be grinded with remaining amount , other dimensions are fixed, leave remaining amount for thickness of pull-tab, and I-shaped groove should be left remaining amount to grinding;
2) Grinding process: grinding thickness, I-shaped groove;
3) Assembly;
4) Pulse;
5) Polishing process;
6) Milling oil groove.

1) Preparation of strip fitter: reserved bilateral height dimension 1.5mm, width direction dimension of bilateral reservation 0.5 mm, 5 mm reservation bilateral longitudinal direction to facilitate clamping cut line processing;
2) Milling process: drilling and tapping screw holes;
3) Heat treatment process;
4) Grinding process: grinding six-sided square ruler, width dimension grinding;
5) Wire-cutting fast-wire processing I-shaped groove, pull-tab, thickness residual grinding machine, height dimension is 1.2 mm;
6) Grinding process: Outer dimensions of grinding are matched with ejector plate and height is 1mm.

1) Wire cutting process: fast wire cutting shape, leaving a grinding reserve;
2) Grinding process: grinding six-sided square feet, dimensions are fixed;
3) Milling process: threading holes, screw holes;
4) Wire cutting process: fast wire cutting oblique guiding hole.

1) Preparation materials;
2) Grinding process: grinding six-sided square feet, dimensions are fixed;
3) Milling process: drilling through wire hole, drilling and tapping screw hole;
4) Wire cutting process: fast wire processing oblique guide column hole;
5) CNC finishing: size of forming part is milled.

1) Preparation materials;
2) Milling process: drilling screw through hole, forming part is rough (single side reserved 0.3-0.5 to grinding);
3) Grinding process: grinding six-sided square ruler, dimensions are fixed and formed.

1) Preparation materials;
2) Grinding process: grinding six-sided square feet, dimensions are fixed;
3) Wire cutting process; fast wire forming;
4) Milling process: drilling and tapping screw holes.

 

Ejector hole of Φ3 or above (including Φ3, Φ4, Φ5, Φ6) is machined by drilling and reaming; below Φ3 or non-standard ejector hole, wire cutting is used, bottom avoidance.

When all kinds of holes need to be cut and inner wall circumference is larger than Φ3 or more (including Φ3), wire holes must be drilled.

1) After finished milling, trademark will leave a margin;
2) Middle wire cutting process: trademark insert hole;
3) EDM: depth of hanging platform;
4) With brand core, assemble fixture;
5) Balance of trademark is leveled by pulse;
6) Polishing process.

1) Milling process: inner frame chamfering, drilling screw hole, thimble hole, waterway hole, gate cup through hole, inclined top hole through hole;
2) CNC machining: milling nozzle cup countersunk, inclined top seat hole, guide block hole, slide groove. Hot runner die A plate requires CNC machining and die lettering processing.

Processing of mounting frame with grid ribs selects different processing techniques according to different mold types.
1) For mold type one, we directly use integral electrode to ensure uniformity of product;
2) For processing of non-type molds, it can be adjusted according to actual processing amount. Electrode can be split or integrated. If rib is a through groove, rough first and finished grinding.

For some parts of workpiece that require wire cutting fixtures or electrodes, batch pulses, processing flow is as follows:
1) CNC machined of layout drawing;
2) Wire cutting drawing is processed by a size fixture or an electrode;
3) After wire cutting process is completed, if electrode still needs CNC machining, electrode is handed over to CNC, and jig is handed over to fitter;
4) CNC machining electrode and making discharge diagram;
5) Pulse processing;
6) Polishing.

Height of support column below 3030 is 0.08-0.1mm higher than mold foot, 3030 is 0.1mm, 3535 is 0.1-0.12mm, and 3535 is 0.12-0.15mm.

 

Cutting processing size of ejector pin more than Φ2 leave remaining amount to grinding, grinding processing size is fixed. Cutting processing size of ejector pin belowΦ2 is fixed. Flat thimble and cylinder are made of wire cutting length, leave remaining amount to grinding.