Multi-Component Injection Molding Process Of Automobile Lamp

Introduction

With the development of the national economy, the automobile industry has become a pillar industry of a country. The rapid development of the automobile industry has put forward higher and higher requirements for automobile lighting. The quality of automobile lighting is an important factor to ensure driving safety. Therefore, countries in the world have made strict requirements for automobile lighting in their laws and regulations.

Now, increasingly richer automobile lamps, including head lamps, tail lamps, fog lamps, turn signals, bumper lamps, brake lamps, width lamps, reverse lights, high mount stop lamps, license plate lamps, hazard warning lamps, and courtesy lights, have been developed.

Lamp design should comply with safety requirements in laws and regulations and meet the needs in other aspects, such as to be integrated with the car shape, beautiful and practical, in line with aerodynamic requirements, so that drivers and passengers feel comfortable and convenient. Therefore, the current lamp design technology is changing amid the development of the automobile industry.

Automobile Lamp Material and Molding Analysis

Automobile lamps are usually composed of a base and the lenses of automotive light. The base is usually made of BMC (a thermosetting material), while the lenses of automotive light can be made of PMMA, PC materials, and is usually two-component, three-component, or even four-component. In the actual injection molding production, the flow performance and mold structure of different plastic melts vary greatly, and the production environment and process conditions are very different, making it difficult to control the product quality. Hence, in the production process, it is necessary to adjust the process parameters repeatedly to optimize the yield and product quality.

Single-color head lamps

Two-color head lamps

Read more: Evolution trend of automobile lamp

Two-color tail lamps

Three-color tail lamps

Four-color tail lamps

Click: Application of auto parts

In the production process of a two-component lamp, special attention should be paid to the injection aspects of the two-component injection molding machine. The center distance of the two screws should correspond to the center distance of the two-component mold. Attention should be paid to the following problems in the production process:

Lamp Type, Material, and Molding Relationship (as shown in the figure) ↓

Photo: Large Horizontal Rotary Table Two-Component Injection Molding Machine (HB-R Series)

1. Important Elements for Stable Lamp Molding
   
2. Design of Special Screw Feeding Tube Set for Automobile Lamp
   • Design FAQs
     • The screw rotates without feeding
     • The screw cannot rotate as too large a torque is required
     • The plastics have not completely melted
     • Screw measurement is not stable
     • The plastics are unevenly mixed
     • Low-temperature molded plastics are easy to heat up
     • There are bubbles in the moldings
     • The moldings are prone to having dark spots or turning yellow
     • The screw corrodes and wears easily, and has a low service life
   • Key Points of Design
     A plasticized screw tube set is the injection molding machine's significant component, responsible for the delivery of plastic raw materials, melting, mixing, measuring, and other functions. Therefore, plasticized screws are an important factor influencing the quality of moldings. The main purpose of the improved plasticized screws is to:
     • Improve shear mixing.
     • Mix evenly.
     • Improve plasticizing capacity.
     • Ensure uniform melt adhesive temperature.
   • Example: Key points of the design of a special screw for the tail lamp
     • L/D: 21-23
     • The surface should be extremely smooth to avoid material deposit
     • Add corrosion resistance process for electroplating thickness
     • Compression ratio: 2.3/ Feeding section: approximately 50%/Compression section: approximately 30%/Measuring section: approximately 20%.
3. Solutions for the Poor Automobile Lamp Injection Problem

   	Solution
   Burns	Reduce injection pressure by multi-section low-speed injection, and vacuumize the mold
   Crazing	Thoroughly dry the injection molded particles, improve the back pressure, reduce the melt adhesive temperature, and reduce the injection rate
   Bubbles	Increase the back pressure, reduce the melt adhesive temperature, use a desiccant dryer, and increase the gate or conveyor size
   Joint line	Increase the melt adhesive temperature, enhance filling speed, and improve exhaust and mold temperature
   Burrs	Improve clamping force, reduce filling pressure and melt adhesive temperature
   Shrinkage	Adopt a uniform thickness design, increase the dwell pressure and time, and replace the back pressure valve

Summary

As automobile outward appearance is constantly updated and lightweight technology has been more and more widely used, FCS Group has accumulated rich experience and technology in the field of plastic parts for automobile lamps and interior and exterior decoration, especially in two-component and multi-component injection molding, making it the first choice of many automobile parts manufacturers.