Injection Mold, Hot Runner, Quick Mold Change

diffusion treatment process we can take a base steel and harden the first hundred microns of the surface to Rockwell hardness well above 65. The rest of the steel remains unaffected.” This is the replacement for Hard Chrome in any big mold. Vermland adds that a large steel mold of 65 HRC could not even be manufactured due to its size. With the surface now harder than that of the glass fibers and any additives, repairs and re-polishing are reduced as much as 80%, according to some customer experiences. “Now the OEM or Tier manufacturers can run many more shots before they have to stop the machine for cleaning or to perform repairs because the surface is much harder. It also prevents residue build-up caused by out-gassing,” adds Vermland. The BALITHERM PRIMEFORM diffusion treatment is also ideal for automotive plastic parts with mirror-polished surfaces, such as those used to produce bumpers headlights, tail lamps, and brake lights or large interior parts with high quality demand like piano black. The mirror-polished surfaces of plastic injection molds are very sensitive and so require more surface cleaning, and protection. Failing to do so can allow dust and other particles into the mold that influence the quality of the end product. With its superior polishing properties, BALITHERM PRIMEFORM improves surface brilliance and eliminates the need for mirror re-polishing after cleaning. In this way, heavily stressed areas are rendered wear resistant and are protected against scratching, environmental factors and improper handling. PVD Coatings for Cavities, Moving Parts For injection mold cavities, fixed items such as guide pillars and sleeves or for moving and sliding components within the mold, carbon-based, physical vapor deposition (PVD) coatings can be applied to prevent galling and wear. “When you apply carbon-based coating to these types of components, you can extend service life, enable longer runs between repairs and increase performance,” says Vermland. Carbon-based coatings such as BALINIT C, BALINIT TRITON or BALINIT DYLYN from Oerlikon Balzers, are thin (approximately 2 – 3 microns) and provide extremely hard layers to the surface of components and cavities. The most critical advantage of PVD coatings is its ability to increase wear resistance over uncoated steel. In fact, all PVD coatings are harder than the steel onto which they are being applied. This hardness and wear resistance is particularly effective against high-filled glass resins and corrosive gasses, emitted by polymers such as PVC. Another reason injection molders employ Carbon based coatings is because of its lubricity, which provides sliding wear resistance for slide-type components like ejector pins, subsequently, protecting them against seizure and corrosion. This lubricity also facilitates the plastic flow, allowing for faster mold filling without the use of internal lubricants and release agents. Because the plastic meets less resistance during injection, less pressure is required. The result is a higher quality end product. Moreover, by coating sliding parts with carbon-based coatings, the need to apply grease is eliminated. Subsequently, only minimal cleaning is necessary, resulting in a significant reduction in production downtime. “You cannot eliminate maintenance altogether, but you can lower the frequency that you have to stop and clean,” explains Vermland. “That means you can run for a longer time and when you do have to stop, you don’t have to replace parts because they are still in good condition due to the very hard coating.” For optimal results, Vermland suggests any customers decide on the coatings for a specific application before choosing the type of steel. Customers often base coating choices on the steel and heat treatment when it should be the other way around. “The proper coating should be determined while designing the mold,” says Vermland. “Once this is done, the ideal coating can be applied in the suitable areas to improve the performance, extend the mold’s life and, subsequently, reduce maintenance, downtime and cost of ownership.”