Car bumpers are one of the most important exterior parts of a car. It not only has sufficient strength and rigidity, but also acts as a buffer in collision accidents, protects the body, and pursues harmony with the shape of the body. In order to achieve these goals, the current car bumpers are made of plastic, commonly known as plastic bumpers.
The shape of the front bumper of the car is similar to the shape of the saddle. The material was PP+EPDM-T20 and the shrinkage was 0.95%. Among them, PP is the main material of the bumper. EPDM can increase the flexibility of insurance coverage. T20 means adding 20% talc to increase the stiffness of the cap.
The characteristics of the car bumper shape are:
1. The shape is complex, the size is large, and the wall thickness is relatively small, belonging to large thin-walled plastic parts.
2, K / Os, S / Os, ribs large, resistant to melt flow.
3. There are three undercuts on the inside of the car bumper, and it is quite difficult to draw the core horizontally at each position.
The conclusion is:
1. Adopt internal classification technology to ensure the appearance of plastic parts.
2. The shape of the car bumper adopts the “composite inclined roof” secondary core-pulling structure, which solves the problem of lateral core pulling of complex parts.
3. The eight-point needle valve type sequence valve hot runner casting system is used to solve the problem of melt filling of large thin-walled plastic parts.
4. Hydraulic pressure is used as the power of the demoulding system, which solves the problem that the plastic part has large demoulding force and the pressing piece is difficult to reset.
The purpose of having a bumper on your car is very specific. Many people think that its purpose is to prevent or lessen injury severity in a crash. In fact, many consider bumpers to not be safety features that protect occupants at all. The purpose of bumpers is to reduce or prevent physical damage to the front and rear of vehicles in low-speed crashes. By design, bumpers protect the hood, trunk, grille, fuel, exhaust, and cooling system. A bumper is a shield that is usually made of steel, aluminum, rubber, or plastic. It absorbs shocks from car accidents.
Production Standards
The standard requires protection in the region 16 to 20 inches above the road surface. It also says the front and rear bumpers should prevent damage at barrier impact speeds of 2.5 mph across the full width and 1.5 mph on the corners. The manufacturer can do these things in whatever way they prefer. For example, they don’t have to have one go totally across if they have bumper guards and corner guards placed strategically. You might think that all vehicles have to follow the Federal Regulations for bumpers. But, that is not the case. this Federal standard only applies to passenger vehicles: cars, SUVs, minivans, and pickup trucks. No other vehicle type has these regulations. This is because a bumper could compromise the loading ramp operations or off-road situations.
Most of the plastic parts in automotive are injection molded.
Bumpers
Trims
Covers , enclosures,
Mounting brackets
Everything else which doesnot take load
Learning the Ins and outs of Injection moulding part design would give a fairly good idea.
A good hold on CAD is required as these part get really complex especially trims parts.
OEMs follow a certain guideline when designing features in plastics. Certain thumb rules and methodologies which are standardized . Highly confidential though.
Having discussed with a few colleagues in those areas , it mostly comes down to wall thickness, ribs and fins for stiffness and feasibility of smooth flow of plastic to not cause any defects.