Introduction to injection mold making and maintenance!


In order to reduce the cost of mold making and maintenance operations, shorten the manufacturing cycle, ensure the life of the mold, and ensure the quality of the product.
1. Production mold number:
1. The mold number must be processed by a milling machine on the outer end surface of the mold blank (square iron), the character height is 40mm, the depth is 0.5mm, and the font is isoline.
2. Each template must be marked with the china mold number with a word code, and the direction is uniform.
3. All screws, hanging ring holes and mold parts of the mold must be of metric specifications, and the accessory mold parts must be of standard specifications, and it is forbidden to make them by yourself.
Second, the mold position
1. Each set of molds has prying positions milled on the four corners of the B plate (moving template) for FIT molds and mold repairs.
Three, code model pit:
1. The non-I-shaped mold blanks need to be milled out of the code mold slot at the front and rear molds, and the specific size is determined by the design size of the mold.
Four, code mold screw hole:
1. Each set of molds must be opened on the movable mold bottom plate and the fixed mold panel.
2. The size of the hole spacing needs to be determined according to the injection model
Five, top stick hole
1. The bottom of the movable mold must have a large enough top rod hole with a diameter of Φ25~40mm.
2. Small molds only need to open one ejector hole, medium molds must open more than three ejector holes, and large molds need to open five holes.
3. The aperture and position of the top rod are based on the actual size of the injection model (designed size).
Six, positioning circle
1. Each mold must be equipped with a positioning ring (ie positioning flange) to facilitate the positioning of the mold.
2. The size of the positioning ring should be determined according to the diameter of the wallboard of the injection model.
3. The diameter tolerance of the positioning ring is 0.2~0.4mm, and the height of the protruding die panel is at least 8~10mm.
4. The standard size of the positioning ring (flange) of the mold and the machine plate is 100mm-0.20^-0.40mm.
Seven, reset the device first
1. When the ejector tube of the thimble interferes with the ejection device of the row position, a first reset device must be installed on the mold, and the thimble plate is not reset by the spring, so as to prevent the spring from failing in the future, and the row position (core pulling) and the ejector tube of the thimble Collide.
2. A travel switch must be installed between the thimble plate and the movable template to ensure that the reset device is effective before powering on and closing the mold.
Eight, thimble plate guide post guide sleeve
1. The length of the thimble plate is 12 or more, or the position of the mold is off-center.
2. It is equipped with many small thimble and the diameter is less than 2mm.
3. It is equipped with more tubes (10 or more).
4. In the above three cases, four guide posts and guide sleeves must be added to the thimble plate to ensure that the thimble can eject the plastic parts in a balanced and stable manner.
Nine, thimble plate spring bow
1. All molds must be equipped with four reset slingshots on the thimble plate to help the thimble retract evenly.
2. The blue slingshot for plastic molds is used, and both ends of the slingshot are ground flat.
3. The reset slingshot cannot be compressed more than 40% of the free length. Four ejection limit nails must be made on the thimble panel when the plastic part is effectively ejected.
4. To fix the reset slingshot, there must be fixed counterbores at both ends, and the unreliable practice of grinding the plane at the other end is prohibited.
10. Automatic dehydration device
1. The thin nozzle mold (three-plate mold) must be equipped with tie rods, tie bars or return pins to ensure that the nozzle plate and A plate move to the nozzle to fall off automatically.
2. The thickness of the bracing material is 10mm or more than 12mm.
3. The diameter of the brace screw cannot be less than 8-14mm.
4. The surface of the B board (moving template) is equipped with 4 nylon rubber nails (nylon drawing machine), the effect is safe and reliable, economical and practical.
Eleven, thimble action
1. It should be ensured that the beer parts can be ejected reliably in any occasion, and it should be ensured to reset without interference with other mold parts before closing the mold.
2. The beer parts cannot be deformed when being ejected, the top white and stuck phenomenon will be ejected quickly and the thimble traces will not affect the appearance quality of the beer parts.
3. The ejection should be balanced and smooth. There should be no tilting of the ejector plate, and there should be no noise during ejection.
4. After the ejection is completed, the thimble should retract automatically (except for special molds).

Introduction to injection mold making and maintenance!
12. Position action
1. The movement of the slider (line position) should be smooth, to ensure that the shape does not move, and there should be no dead movements, unevenness, looseness, etc.;
2. The sliding guide surface of the large slide block must be provided with an oil groove;
3. The large sliding block must have a cooling water channel;
4. The sliding block and the sliding seat part are matched with HVE6, which should not be too loose;
5. When the sliding stroke length of the slider is too long, the guide must be extended on the mold base. Generally, the length of the sliding part should be about 1.5 times the width. When the core is pulled, the mating part of the slider in the guide groove must have a slider. Two-thirds of the sliding part of the pipe is in the guide chute;
6. There must be a clearance of 0.2mm or more between the inclined guide post hole and the inclined guide post, and the same size fit is forbidden;
7. The angle of the inclination guide post is less than 2 degrees of the inclination of the clamping surface of the travel position. The clamping block of the large slide block must be extended 15-20mm into the lower mold, and interlocked back pressure with a 10 degree inclined surface.
8. For the cavity of the round slider combination, the angle between the longitudinal direction and the taper surface of the wedge slider, and the angle of the slope column are different by 2 degrees. The same degree is forbidden. The final positioning of the slider above the mold must be pushed or pulled by a slingshot. , Do not use wave beads in form, so as not to damage the clamping block and the oblique guide column when the slider is in mold clamping.
9. The rubbing surface of all rows must be equipped with wear plates, the length of the rubbing surface is ≥30mm, and the width is ≥50mm. The fine row position and the row position pressing plate need to be quenched and hardened more than 52 degrees, and the large row position is nitrided or hardened according to the requirements before mold opening.
13. Hanging die hole
1. There are hanging mold screw holes on the bottom and bottom of small mold A and B;
2. All templates of large molds are provided with hanging mold screw holes, or both sides are required.
14. CAV NO.:
1. One-mold multi-cavity parts must be marked with CAV NO. on the non-exposed surface to show the difference, and they must be finished before the first mold trial.
2. The position of CAV NO. should be marked after contacting the design engineer.
15. Material channel shape
1. In principle, use cnc  parts O-shaped (circular) material channel;
2. Trapezoidal forehearth is used in special circumstances;
3. The size of the cross-section of the sprue opening is usually determined according to the size of the product and the number of sides of the cavity of the mold, and the specific size is determined according to the mold design drawing;
4. There are many shapes and styles of sprue openings, usually flat, flat, point pouring, submersible, three or four-claw point pouring, the specific material pass size is positive or negative with the actual product size, and the flow rate should be distributed when opening the material pass. Uniform, usually the farther away from the main runner, the sprue opening gradually increases. The fine nozzle point pouring type. In principle, the belly button should be retained. Generally, the sprue opening should be cut obliquely when the water enters to prevent the product glue from increasing the auxiliary manual workload after the nozzle.
16. Special-shaped thimble, insert
1. When the special-shaped thimble insert can be rotated, an anti-rotation device must be made.
2. The anti-rotation device must be reliable, single orientation, positioning in two directions is forbidden, (including the inclined surface of the cylinder needle)
17. Sitong
1. All the holes of the cylinder must be reamed and cannot be drilled directly, so as not to burn the column forming part of the cylinder, the beer handle must be processed, and the light is saved to avoid circles or whitening of the rubber powder.
2. Priority is given to the use of standard cylinders, and it is strictly forbidden to use as many sizes as the diameter of the forming part is. The cylinder size can be smaller than the outer diameter of the forming column;
3. In order to avoid the eccentricity of the cylinder and the cylinder, the cutting amount of the cylinder head should not exceed 10 mm, and the size must be considered when designing and purchasing.
Eighteen, exhaust slot
1. Exhaust grooves must be milled on the back of the guide sleeve of the fixed template (A plate) to prevent the formation of vacuum from affecting the beer and FIT molds, and increasing the hydraulic energy for opening and locking the mold will damage the machine parts;
2. In order to ensure high-speed injection, the final welding part of the mold parting surface and the end of the material passage must be opened with an exhaust groove.
3. For the depth of the exhaust slot, please refer to the parameters: ABS, AS, PS machining uhmw plastic: 0.03mm, PC, PE, PP, PM: 0.02mm, PA nylon 0.01mm.
4. For the precise exhaust position, the exhaust groove can be processed after the first mold trial. The exhaust groove must be processed by grinding hemp or milling machine. Grinding machine is prohibited.
19. Prevent the mold from rusting
1. All cnc brass parts in the mold manufacturing process must be coated with anti-rust oil after the suspension of processing to avoid rust;
2. The outer side of the mold blank should also be sprayed with anti-rust oil after removing the mold to prevent rust.
3. There must be no rust marks when the new mold is finished.
Twenty, thimble barrel burns
1. New molds must not have defects such as thimble barrel welding.
2. The thimble hole must be lighter.
3. The bottom of the fixed counterbore of the thimble hole and the cylinder needle must be flat, and the axial fit clearance should not be greater than 0.15mm.
4. The hole tolerance of the matching clearance between the thimble cylinder and the core is H7.
5. High temperature thimble oil must be sprayed between the thimble cylinder and the hole.
6. The thimble must be higher than the cavity surface by 0~0.5mm and must not be lower than the back mold surface
21. Cooling water access mark
1. The cooling water outlet must be marked with “OUT” or “O”, and the inlet must be marked with “IN” or “I”
Twenty-two, marking the thimble
1. The thimble fixing plate must be marked with a mark, the mark should be the same and in the same direction, so as to modify the mold
2. A mark must also be placed between the insert and the fixing plate to prevent incorrect installation.
Twenty-three, the parting surface is higher than the mold surface
1. Usually the parting surface is 0.1-0.5mm higher than the mold surface.
24. Demagnetization of slider and inclined top block
1. The moving parts (fast sliding, inclined top block, wedge block) must be demagnetized after grinding to avoid burning the moving parts and under the action of magnetic suction, the slider will return to the original position after it leaves. Bump the slider.
Twenty-five, runner polishing
1. The runner must be polished, and it is strictly forbidden to emboss on the runner, so as not to affect the injection fluidity and the appearance of the beer;
2. The length of the main runner is less than 60mm if the structure permits.
26. Is the flow path and water inlet reasonable?
1. The flow channel should be set up to ensure the balance of the water inlet and reduce the nozzle material, and the cold material hole must be set at the turning point of the flow channel;
2. Priority is given to the use of hot runner diving ports to save materials for the nozzles, and to ensure that the product requirements for water intake are as low as possible to reduce auxiliary labor costs.
27. The inner and outer mold planes must be parallel, and the height of the 4 back clips must be the same.
Twenty-eight, the movement of the nozzle plate must be balanced and evenly opened, and the stroke is reasonable.
Twenty-nine, mold saving must ensure that the mold is not sticky, not white, and must meet the product requirements.
30. Auxiliary column (mould top, support head)
1. The mold should be equipped with auxiliary columns as much as possible, in the center as much as possible, and as large as possible in each diameter;
2. The auxiliary column must be fixed on the bottom plate of the movable mold with screws;
3. The length of the auxiliary column should be longer than 0.1-0.25mm of the height of the mold square iron
31. Frozen water
1. All cooling water must be uniform and sufficient, and the diameter of the cooling water cannot be smaller than Φ8mm or Φ3/8″, unless the structure does not allow it;
2. The sealing rubber ring must be 0.5mm higher during processing;
3. Do a water pressure test, under 8Kg pressure, no water leakage for 5 minutes.
Thirty-two, nitriding
1. Before opening the mold, in addition to specifying all the steel materials, after all the projects are completed, the surface must be nitrided. There are two requirements for nitriding:
1) All moving parts (including row position, inclined top, rub-through position, inclined shovel), etc., these parts need to be nitrided for fixing.
2) Individual molds require all nitriding (including PC, nylon and iron… and other engineering materials, and these molds must be specially prompted for all nitriding before opening.
Thirty-three, the first trial
1. When the new mold is tested for the first time, the shape of the mold must be the model and name of the company’s mold;
2. The first trial of the new mold must be equipped with standard positioning parts for moving and fixed molds, one on each side.
34. The new mold must be a standard mold base.
Thirty-five. The four corners of the new mold core must be positioned for the mold core.
36. All molds must be equipped with movable and fixed mold locks.


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