More than ever before, vehicles are changing and automotive suppliers under pressure to adapt, and quickly. Enhanced driver experience and connectivity features are demanded by consumers, and with it new performance standards and challenges, and strict environmental and safety requirements.
Automotive manufacturers and their supply chains must meet these demands for high performance, reliable products. LSR automotive parts such as seals and gaskets, wiring harness components, and 2-shot high-speed sealed connectors and sensor housings, are examples of parts used throughout the vehicle that must rise to the challenge.
SIMTEC Silicone Parts is relied upon by Tier 1 and Tier II automotive suppliers for innovative solutions to meet their requirements. For nearly 20 years, SIMTEC has supplied consistent, high-performance, high-volume Liquid Silicone Rubber (LSR) components to manufacturers in the automotive industry.
HIGH OUTPUT COMMANDS HIGH CAVITATION
To meet the needs for high volumes in automotive business, high-cavitation molds are used. “Cavities” are the open areas in the mold that form the parts. The more cavities in a mold, the more parts that can be produced every time the mold opens and closes (a molding cycle). In addition to added capacity, high cavitation molds offer optimum productivity and efficiency and meet cost-down objectives—all very important in the highly competitive auto industry.
SIMTEC provides customized solutions that deliver a level of quality like none other.
In this article, we discuss some of the challenges that exist with high-output needs and how SIMTEC’s technologies offer great resolution.
HIGH OUTPUT PRODUCTION CHALLENGES
Automotive manufacturers need high volume production, and although attractive to manufacturers that supply the OEM’s, it does present challenges.
The greatest challenge in high output LSR injection molding is maintaining process stability across all cavities. Take a look at several concerns that can come up during high volume manufacturing and the methods and solutions SIMTEC has developed to address each challenge.
When producing a high volume of parts with one high cavitation LSR mold, it’s imperative that the material is exposed to the same temperature in all cavities, from center to the far corners of the LSR mold or else quality suffers due to differences in fill or curing. To help improve thermal management during the molding process, SIMTEC uses well-balanced cold decks and cooled nozzles to keep the LSR from curing too soon. This cold deck and nozzle technology are proprietary and developed by sister-company RICO. When used with direct gating, the material is injected into one or only a few parts, minimizing or eliminating the runner thereby reducing the distance the material must travel and further reducing the potential of overheating the material. When gating directly into a part, flash is minimized and assists in maintaining tight tolerances.
BALANCE IN MATERIAL FLOW
When an LSR mold has multiple cavities, there is the risk that the cavities won’t be filled equally or at the same rate.
Imbalances in cavity filling can lead to incomplete parts, called “short shots,” or flashing occurs when excess material forms at the end of the part.
SIMTEC’s open nozzle design allows the material to return to the cold runner as it expands, helping to improve balance and reduce the risk of both, short shorts and flashing. The same goes for the needle valve gate technology. In this case needles close the opening of the nozzle tip, shutting off the flow of material. Here balance in the cold deck and consistent uniform fill across cavities is key for consistent parts across all cavities. SIMTEC’s mechanically actuated needle valve system allows for fine-tuning in the process, but the goal is to make as little adjustments during the run as possible.
CAVITY-TO CAVITY PRECISION
In a true 2-shot molding process, the molds for producing the plastic and LSR components are in the same molding machine producing the plastic and LSR components in the same cycle. The in-cycle transfer between the plastic and silicone cavities must be meticulously tuned in order to get in-spec 2-shot parts. Smooth transfer, precise alignment and proper shut-off is particularly challenging in a mold with a large number of cavities. If the cavities are not precisely aligned, even by the smallest of margins, the parts may show flash or deformation, or may not be able to perform as designed, resulting in parts that could be rendered unusable.
SIMTEC’s two-shot technology provides precise cavity-to-cavity designation for high precision parts and superior adhesion. SIMTEC focuses on precise uniformity, from the barrel to each cavity, and cavity-to-cavity.
DEMOLDING LARGE QUANTITIES OF PARTS
A mold must also have an efficient and effective option for removing the parts from the mold once they are made. One of the challenges of using a high cavitation mold is removing the large number of parts, quickly and efficiently so production doesn’t need to slow down to get parts out of the mold.
SIMTEC uses fully automated, custom-designed demolding technology. The parts are removed using a three-axis robot with customized end of arm tooling.
In SIMTEC’s largest-ever, high-cavitation mold, a 96 + 96 cavity mold (96 LSR cavities + 96 thermoplastic cavities), two-shot sensor components are produced. The components are removed using specially-designed end of arm tooling, custom-built with carbon fiber to accommodate the high cavitation, and so as not to exceed maximum load on the robot. Once the parts have been removed from the mold they must then be collected and post-cured. SIMTEC devised a customized method for collecting, segregating and identifying the parts by cavity. The cavity separation allows for better traceability and containment.
CONTAINMENT FOR IN-PROCESS INSPECTION
It is common and a good quality practice for in-process inspections to take place. Samples are taken on a timely basis by quality assurance inspectors during the production process. Key, critical dimensions are measured and documented. This serves as verification of process stability, dimensional integrity, and confirms that parts are being produced within customer-defined specifications. When parts are separated by cavities it provides for good traceability and containment as problems usually start with specific cavities. If inspection finds a sample is out-of-spec or suspect, parts from the specific cavity can be contained and held for further investigation. This allows the remaining good parts in the production run to not be delayed and can ship to the customer.
PRODUCING STABLE RUNS
Process stability is essential when producing parts, as each part needs to be the same as the one before it and the one after it. During production, there is a risk that deviations will occur as a result of fluctuations in temperatures or other process variations.
The mold technology is a key element for the stability of the LIM process. SIMTEC uses high quality RICO molds featuring smart-centering design, precision machining and high durability materials for stable runs and minimizing the risk of defective products.
HIGH CAVITATION ON SMALL PLATENS
High cavitation allows more parts to be produced at the same time. SIMTEC specializes in small parts with small shot weights, including tiny micro molded parts. High cavitation using small machines with small platens can be difficult. To overcome this challenge, SIMTEC uses proprietory dual-tip nozzles developed by mold supplier and sister company RICO. This special nozzle, developed specifically for use with small platens, features an optimized nozzle design to allow for easy filling of multiple cavities on a small machine.
SIMTEC SILICONE PARTS’ HIGH VOLUME AUTOMOTIVE PARTS
SIMTEC provides Tier I, and Tier II suppliers with the solutions they need. Our automated molding technology allows us to manufacture high volume, LSR single- and multi-shot LSR parts, such as seals, gaskets, specialty O-rings, sensors, and connectors to the precise specifications of our customers. Our technology is specially designed for highly-automated, long-term production using our proprietary technology and custom designed manufacturing cells. SIMTEC’s precision molds, excellent process stability, and technology ingenuity allow us to redefine the possibilities.
Since 2002, we have built a reputation for providing extraordinary solutions(TM) in LSR for our customers. We work closely with our customers to provide custom solutions to meet their high volume, high performance requirements. Contact a SIMTEC representative today.