Production technology of silicon rubber keys: in electronic computers, remote control system, electric toys, telephones, wireless telephone, you need to use the key, the early button is composed of plastic button with metal spring, its disadvantage is need to use a thumb strength, operating fatigue for a long time, but also affects the service life; And then changed to electric key, the key is convenient to use but the heavy vulcanization machine is too large; In recent years, developed into the conductive rubber key (to add plastic keys), its structure is placed on the printed circuit board (PCB), conductive rubber key generated by the conductive rubber particle contact PCB and telecommunications, it overcomes the shortcomings of two kinds of buttons, before but when combination is time-consuming; According to its shortcomings, and developed the conductive keys and key words of silicone buttons, raw material is mainly used in silicone rubber. Because silicone rubber has excellent heat resistance, cold resistance, environmental resistance, electrical insulation and fatigue resistance, and many other features. The production process of silicone rubber keys is discussed in this paper.
3.1 for mould
Die buttons are available according to customers drawings or samples processing, mold made of silicone buttons, test confirmation of structure and production process can be mass production. Before production mould generally requires mould sand blasting surface treatment, if the silicone key requirements for the glossy surface is sprayed glass sand, requirements for spray mist is silicon carbide or mixed sand, if no request can be mixed spray sand.
3.2 prepares materials
According to the quality of customer orders, specifications to determine hardness of the rubber and the impression of buttons, according to the formula in the mixing mill mixer machine mixing, according to the test when making out rubber specification sheet with PE film bag; At the same time ready to release agent, conductive adhesive black grain and various tools.
3.3 vulcanization molding
Vulcanization molding using plate vulcanizing machine, according to the function of the vulcanizing machine manual, automatic, vacuum type, etc. Mould by upper and lower two layers of cavities and (miscellaneous pieces of special SanBan mode), production upwards open cavities, male die on silica gel is put in the conductive adhesive black grain, and slice weighing key raw material, if there is demand, is in the master pattern into the color key, when ready for heating, vulcanizing mould clamping. Vulcanization of the main control parameters as temperature, pressure and curing time, the typical operation process conditions for: temperature 160 ℃ + 10 ℃; 15 ~ 20 mpa pressure; Time of 150 ~ 200 s (depending on the height of the keys, such as shorter key smaller 30 ~ 40 s can also be completed). Will launch vulcanizing machine, mold, after the completion of sulfide carefully open cavities, cooperate with air pressure gun, slowly remove the silicone button from the mold.
3.4 second vulcanization
After vulcanization of semi-finished products can be according to customer's requirement to decide whether the secondary sulfide, residual vulcanizing agent to remove products breakdown products, improve the performance of products. Conventional secondary sulfide using vertical oven, with the temperature of 180 ~ 200 ℃ baking 2 h to complete.
3.5 silk screen, fuel injection, laser carving
According to customer's requirement for silicone buttons surface processing on the surface of the product for screen printing, oil spraying, laser carving process, after the completion of the send the quality inspection.
3.5.1 track of silk screen, select the corresponding screen and surface characters of the silk screen printing ink, screen printing after subject to quality inspection, unqualified solvent erase reprint, qualified sent to bake.
3.5.2 injection, according to the customer's requirements on the surface of the silica gel key-press sprayed oil, extinction, PU ink, spray immediately after baking, after baking, unqualified select rework or scrap, or sent to the next process
3.5.3 radium vulture, according to the customer's requirements on the surface of the silica gel key-press laser carving processing.
Cutting, since 3.6
According to the design of the die silicone buttons to choose die cutting or manual since open remove redundant burrs silicone buttons and cut clean, make the surface of the silica gel key-press more beautiful
3.7 process control
3.7.1 vulcanization molding process of the control
This is the first stage of the process control. Main inspection items for size, elasticity, hardness, stain, color difference, lack of materials, etc., to eliminate bad product, discover the significant bad problem, and feedback to improve the production requirement, in order to reduce the generation of defective products.
3.7, 2 screen printing quality control
Inspection on heavy shadow, silk screen is not complete, the font is not clear, poor wear resistance. Wipe away the bad product available white electric oil and other solvents, natural dried to reprint for silicone buttons.
3.7.3 into springtime delights control
Including print, without printing product, has the full inspection, such as check out all kinds of bad product for packaging.
4, the conclusion
To sum up, the production of silicone rubber keys is a complex process, the stand or fall of quality in addition to the machine and human factors. Intermediate inspection is the key to find and solve the major quality problems. Therefore, maintain the normal operation of the machine, mold good working state, strengthen the operation of the operator and qc personnel skills and quality consciousness training is the key to reduce production bad, is also the enterprise benefit.