Views:32 Author:Site Editor Publish Time: 2019-08-27 Origin:Site
The basic knowledge of the mold is to tell the basic composition of the mold, the influence of the shape on the product, and the introduction of the mold model.
1. The basic composition of the mold
(1) Front mold (master mold) (fixed mold), (2) rear mold (male mold) (moving mold), (3) insert (insert), (4) row position (slider), (5) ) oblique top, (6) thimble, (7) gate (water inlet)
2. The influence of the shape of the mold product on the product
Wall thickness, geometric shape, will affect the forming shrinkage, the draft angle
3. Influence of water inlet on shrinkage rate of products
When the size of the water inlet is large, the shrinkage rate is small, and when the size is small, the shrinkage rate is large, and the flow direction is parallel, the shrinkage rate is large, and the vertical direction is closed.
4. The mold wall thickness is too large and the wall thickness is too small
Wall thickness is too large: (1) increase costs
(2) Prolonged forming time and reduced production efficiency
(3) Quality is difficult to control, easy to appear bubbles, shrinkage holes, depressions, etc.
The wall thickness is too small: (1) The resistance of the plastic flowing in the mold is large. If the shape is more complicated, forming will be difficult
(2) Poor strength
If the wall thickness of the plastic part is not uniform, the shrinkage will be uneven after the forming process, and not only bubbles, depressions, deformations but also large internal stresses will be present.
At the junction of the wall thickness and the thin wall, avoid sharp angles, excessive entanglement, and the thickness should gradually decrease along the direction of plastic flow.
5. Rounded corners (R position)
Set the fillet (R position) to increase the strength so that the plastic part does not deform or crack
(1) In order to ensure the strength and rigidity of the product without making the wall thickness of the plastic part, reinforcing ribs may be provided at appropriate portions of the plastic part to prevent deformation, and in some cases, the problem of plastic flow during forming may be improved.
(2) The thickness of the ribs should not exceed 50% of the plastic parts, usually around 20%.
(3) The rib should be lower than the plane of the plastic part
(1) The periphery of the hole is prone to weld marks, which reduces the strength of the plastic part. Note that the distance between the hole and the hole, the hole and the plastic part should generally be more than twice the hole.
(2) The edge of the hole can be used to strengthen the strength of the hole
(3) The depth of the blind hole cannot exceed 4 times the diameter of the aperture
(4) Screw holes should pay special attention to the strength of the hole and the size of the hole. If the hole diameter is too large, there will be slippage after the screw is inserted. If the hole diameter is too small, the screw or the screw column may not be inserted.
(5) The hole column is too long (high) should pay attention to poor mold exhaust
(6) The depth of the aperture does not exceed 8 times the aperture
(7) Holes with steps, the cores are fixed on both sides of the fixed and movable molds, it is difficult to ensure the concentricity, and the burrs are easily generated at the joint positions of the two cores, so the core of either side (aperture) Increase by more than 0.5MM, guided by the other end
8. Mold insert, row position, slant top
The inserts, rows and sloping tops of the mold are usually mounted on the moving mold of the mold. If the fitting is not tight, there will be burrs.
The plastic products made by precision molds have a good performance in terms of precision and quality. The company is committed to providing quality products to customers with the spirit of artisans.