| Injection molding is a manufacturing technique for | | | | reductions. |
| making parts from plastic material. Molten plastic is | | | | Some common molding problems and their remedies |
| injected at high pressure into a mould, which is the | | | | Scorch |
| inverse of the desired shape. The mould is made by | | | | Scorch is premature vulcanization of the rubber, |
| a mold maker from metal, usually either steel or | | | | before the flow of rubber in the mould is completed. |
| aluminium, and precision-machined to form the | | | | The poor mould flow results in distorted or |
| features of the desired part. Injection molding is very | | | | incompletely formed parts. To prevent or eliminate |
| widely used for manufacturing a variety of parts, | | | | scorch, see that the mould is completely filled before |
| from the smallest component to entire body panels | | | | the rubber starts to vulcanize. Assure that the mould |
| of cars. Services offered by providers of liquid | | | | cavity is uniformly heated. |
| injection molding include bonding, design assistance, | | | | Backrinding |
| graphics, tool or mold making, prototype or market | | | | This is distortion of the molded product at the mould |
| entry molding, low volume production, high volume | | | | parting line usually in the form of a torn or a ragged |
| production, micro molding, large part molding, insert | | | | indentation. Backrinding is generally caused due to |
| molding, two-shot injection molding, stamping | | | | sudden release of internal pressure within the part |
| services, assembly services, just-in-time capability, | | | | when the mould is opened. So to prevent it make |
| and packaging and shipping. | | | | sure there is no roughness or excessive opening at |
| Liquid Injection Molding | | | | the mould parting line and keep the molding |
| Nowadays, liquid injection molding is becoming | | | | temperature as low as possible for the vulcanizing |
| increasingly important. One reason for this is the | | | | agent used. |
| increased performance requirements of the finished | | | | Entrapped air |
| rubber parts. In addition, more and more producers | | | | Air entrapped in the mould or the rubber may |
| of rubber parts are seeing the benefits in the high | | | | produce soft, discolored areas in the surface or in the |
| level of automation and productivity. Injection molding | | | | cross section of the molded part due to incomplete |
| technology, using liquid rubber, combines the speed, | | | | vulcanization. Remedies include |
| cost efficiency, and versatility of plastic injection | | | | - Bump the mould |
| molding with the outstanding properties of silicone | | | | - Increase the amount of vulcanizing agent. |
| rubber. It is used in many applications where organic | | | | - Use a high temperature-vulcanizing agent that is less |
| rubber cannot perform, such as military, aerospace, | | | | reactive with air. |
| automotive, healthcare applications, etc. The use of | | | | - Vent the mould at sharp corners and undercuts. |
| silicone rubber combines the properties of resilience, | | | | Surface discoloration |
| high temperature stability and inertness as silicone is | | | | This usually results from excess build up of mould |
| generally unaffected by temperatures from 100 | | | | release agent in the mould cavity, or from excessive |
| degrees Fahrenheit to 450 degrees Fahrenheit. | | | | dust or dirt in the preform. To prevent it clean the |
| Progress in liquid injection molding technology has | | | | mold as often as necessary and keep the preforms |
| made faster cures possible, enabling unit cost | | | | clean. Use release agents sparingly. |