How about surface treatment for high precision plastic injection molds? How does it work?
PC optical bracket of high precision plastic injection mold surface treatment case study
Number of mold cavities: 1*4
Customer Part Name: OPTICAL HOLDER
Product material: PC
Material Model: 121R
Colour: Black
Product net weight: 1.938g*4
Head weight: 2.687g
Estimated weight: 5kg
Machine model: 30T
Customer request about high precision plastic injection mold surface treatment
The red side is EDM texture CH21, the green side is polished texture SPI-B3
Solution:
EDM (Electrical Discharge Machining), also known as spark erosion, uses graphite or copper electrodes placed in a water or oil electrolytic cell. When the electrode reaches the threshold current, it creates a spark on the tool wall. The target melted but was immediately quenched by the surrounding electrolyte. This causes thermal shock, which causes the metal to shatter into tiny particles, which are then washed away.
Spark corrosion works on both hard and soft metals and can produce very tight tolerances. It is ideal for making deep grooves, sharp reentrant corners, debossed lettering and other features that are difficult or impossible to machine traditionally. In addition, very fine and smooth surface finishes can be achieved, eliminating time-consuming and expensive manual polishing.
It is a standard in the United States for high precision plastic injection mold surface treatment finish. If it is steel, I know the effect of processing with 320 whetstone.
Attachment: International Standard Processing Method for Surface Roughness
Standard grade code Surface roughness Processing tool (method) Processing material and hardness requirements Photometric description
Coarse grinding grit size Fine grinding grit size Diamond paste polishing
SPI(A1) Ra0.005 S136 54HRC: Very high finish, mirror effect
SPI(A2) Ra0.01 DF-2 58HRC: Low finish, no sandpaper pattern
SPI(A3) Ra0.02 S136 300HB: The finish is one level lower, but there is no sandpaper pattern
SPI(B1) Ra0.05 No brightness: with slight 3000# sandpaper grain
SPI(B2) Ra0.1 No brightness: with slight 2000# sandpaper grain
SPI(B3) Ra0.2 No brightness: there is a slight 1000# sandpaper pattern, the direction of the processing marks cannot be distinguished
Along with the development of the mold industry, the performance requirements of the high precision plastic injection mold are increasing, and the life problem is becoming more and more profitable. Welcome to the challenge of accepting molds, the market will continue to develop.