From product design, mold design, mold flow analysis, we have a professional team working for bumper mould project and there are more than 15 sets of different size machine which are specially for Mould testing.
Before designing Automotive Bumper Injection Mould---MOLDFLOW
Automotive bumper part is absolutely an aesthetic plastic component with big size and high surface requirements. So before designing the product and mold, it's better to use Moldflow to anaylize the deformation of product, the location of part line, the efficiency of cooling water way, the matter of material filling, etc.
The moldflow will analyze specifically following sections:
1. Flow Analysis Section
fill time; pressure at V/P(velocity/pressure) switchover; temperature at flow front; bulk temperature; bulk temperature at end of fill; shear rate & bulk; pressure at injection location; volumetric shrinkage at ejection; time to freeze; frozen layer fraction; percent of shot weight; air traps; average velocity; clamp force centroid; clamp force; flow rate/beams; frozen layer fraction at end of fill; material source; in-cavity residual stress in first principal direction; in-cavity residual stress in second principal direction; orientation at core; orientation at skin; pressure; pressure at injection location; pressure at end of fill; recommended ram speed; shear rate(Midplane/Fusion); shear stress at wall; sink index; temperature; throughput; velocity(Midplane/Fusion); volumetric shrinkage; weld lines; hold pressure
2. Cooling Analysis Section
circuit coolant temperature; circuit reynolds number; circuit metal temperature; circuit flow rate; product top part temperature; product bottom part temperature; product two side temperature difference; cold runner temperature on mold surface; product freeze time; product maximun temperature; cold runner maximum temperature on mold; product average temperature; product maximum temperature position; product temperature profile; mold boundary temperature
3. Warping Analysis Section
stress in first principal direction; stress in second principal direction; Mises-Hencky stress; stress tensor; strain in first principal direction; strain in second principal direction; strain tensor; maximun shear stress; anisotropic shrinkage; isotropic shrinkage; bending curvature; material orientation; average fiber orientation
After making moldflow, the potential problem in product & mold design can be found, also the possible forming defect of product can be found. So when designing, these problems can be avoided, which can reduce the revise time and save cost. So for high requirements or large size automotive part mold, it's a good choice to make moldflow before design.
During designingAutomotive Bumper Injection Mould
Hongmei Mould has professional designers for checking fixtures specially, who are well know of GD&T drawing. We always obey the following rules:
1. Making the preliminary design exactly based on custmer's GD&T drawings, and making sure all the points on the drawing are checked and tolerance requirements are met.
2. Improving the design according to customer's feedback, and making the mold easier for machining and usage, at the same time, saving the machining cost and decreasing the lead time.
3. Making the design flexible, in case for future repairment easily for our customer.
Mould CNC Processing
Also after finishing design, our project manager will check the rationality of 3D structure, for the bumper product is a large thin-walled injection molding part, also is a exterior part, which requires good performance on material and surface. So below points need to check carefully:
1. Wall thickness
For bumper mold, the wall thickness should be balance, otherwise it will cause uneven contraction because of different speed of solidify or cooling, which at last will cause product warping, transformation or void.
2. Draft angle
Considering the best draft angle, the draft angle larger, it's more easy for demolding, but will cause uneven product thickness, so need to choose a compromised angle number to get a good product.
3. Reinforcing rib
For large size product, only with a certain wall thickness can't guarantee the product shape and size, let alone the certain strength. So in some parts with hole, large hook face or mounting point need to add some reinforcing ribs to increase the strength and stiffness. For exterior product, shouldn't add ribs on CLASS A surface. In CLASS B face, the ribs wall thickness should not more than 3/4 of the product wall thickness. In CLASS C&D surface or some low surface quality requirements parts, the ribs can be added.
4. Round corner
Commonly, the minmum round corner will be R0.5, and to avoid placing the round cornner in joint face, otherwise will add the manufacture cost and difficult.
For the shape of hole should be as simple as possile, also there should be some distance between hole and wall.