Myths have been around: the world is flat along with the sun involves planet earth- to name a few. The world of manufacturing is no different featuring its own false beliefs. Today we certainly have the myth that aluminum tooling is “junk tooling or perhaps for prototypes only”. This really is a stereotype containing grown from earlier grades of Cold stamping molding aluminum that have been gummy, difficult to cut and improperly employed in a manufacturing environment.
The creation of aircraft grade 7075 aluminum brought forth a durable and quality product. In 1998 the SPE and Douglas Bryce wrote “Plastic Injection Molding: Mold Design and Construction Fundamentals” that discussed the quality of 7075 and also the ability to produce an incredible number of parts. However, many manufacturers did not follow his recommendations. Instead, many chose the wrong aluminum alloy and failed to follow good tooling practices. Unfortunately, damages to aluminum’s reputation had already been done.
Cost factors are forcing manufacturers and major OEMs for taking a 2nd take a look at aluminum. In 1991 IBM did a five-year study on aluminum tooling with lots of credible findings. Currently, Honda’s ongoing aluminum tooling study can be a success along with other companies are taking a renewed curiosity about the fee savings that aluminum has to offer. Unfortunately, old beliefs take time and effort to get over.
Aluminum can be used production volumes: The mistaken belief that only steel alloys including H-13, S-7, stainless steel or P20 steel needs to be employed for production molds might be a costly one. An aluminum mold offers volumes between 100,000 approximately 1,000,000 components. This is due to current aluminum grades which are heat treated in their creation process creating a 6 – 18RC hardness. Surface coating treatments can harden aluminum approximately 56 – 62RC depending on this process. When these hardness levels are when compared with P20’s 28 – 32RC and 420 stainless steel’s 34 – 38RC (pre-heat treated), this estimate of one thousand,000 seems conservative.
All resin types may be used on aluminum: Aluminum’s excellent thermal conductivity allows resins to flow more evenly than steel. Certain resins like clear acrylics and polycarbonates often have processing issues due to cold and hot spots in a mold. Aluminum’s even heat dispersion reduces these areas resolving bubble along with other aesthetic issues. Other high-temperature resins can run successfully in aluminum with cartridge heaters which can be normally used with steel molds. Difficult-to-fill resins having a high viscosity rate also reap the benefits of even heating mainly because it reduces sheer stress upon the information by balancing the flow of material using a hot runner system. Glass-filled along with other abrasive resins can be run with success so long as special care is taken to either hard coat or steel insert critical areas. Glass-filled resins can actually run more proficiently with aluminum because of its consistent thermal conductivity that assists in the flow of resin. PVC is normally incorrectly believed to be abrasive, if in fact it can be corrosive. For this reason steel alloys are chosen over P20. Both stainless and aluminum are corrosion-resistant naturally. Aluminum forms a .000001 (microinch) self-healing layer as a response to oxygen called aluminum oxide. The chromium in steel reacts much the same way to oxygen forming a layer called chromium oxide. Some of the newer grades of aluminum have chromium added for greater corrosion resistance. There are surface hardening processes that work well with PVC that could increase component output.
The saying “production” is subjective, as Medical PCV sheet can achieve high volumes: How does “100,000 – one thousand,000 production-quality plastic parts” sound? Not quite short-run or low-volume. For most projects this is ample for the project up until the next design change or upgrade. Naturally higher production quantities can be accomplished based on the resin and design. Aluminum tooling is also excellent for keeping marketplace share when bridge tooling is necessary. An added benefit is that if the tool life is exceeded, aluminum is forgiving and straightforward to keep or enhance in order to get those last few plastic parts before the hardened steel production tool is ready.
Unlimited surface finishes: Almost any surface finish or texture that could be applied to a steel mold can be applied with an aluminum mold. This includes Class A diamond finishes (SPI A-1), which can be needed for chrome plating. Certain grades of aluminum will be more appropriate for this, which can also need a hard coating process to improve this finish. Bead blasting or any aesthetic texture finish can be achieved with success.
Faster process cycles: As outlined above, the thermal conductivity is a benefit that eliminates many processing issues. Fast and even air conditioning contributes to less shrink and warpage issues from uneven heat dispersion. Less scrap can be a saving money, but cycle times may also be reduced by 30 percent typically, bringing down overall piece price. In order to run aluminum, a molder will need good tooling practices and maintenance routines to improve the tool life and fully realize every one of the cost and time savings. This consists of watching parting lines and shutoffs for wear to eliminate parts sticking and excessive wear. A sticking part may damage aluminum tools worse than steel. However, in case the tool was built correctly and maintained to industry standards, it is really not a standard occurrence.
Design modification: Commonly, many projects from the planning and design verification stages proceed through some kind of design modification. Aluminum could not be simpler to modify or groom for max efficiency when during the build or as soon as the tool is running parts, modifications towards the initial design or even to troubleshoot production issues are essential. Welding aluminum has become very successful recently, that enables consideration for even cosmetic changes as well.
No design restraints: Complex design geometries which require under cuts, which require mechanical slides, lifters or hand loads can be accomplished exactly like inside a steel mold. Careful project planning, a powerful knowledge of mold design, together with experience in machining aluminum means there is no reason never to expect aluminum to keep dexjpky71 dimensions. Steel inserts enables you to further maintain critical areas for higher volume projects. This will all be carried out in a shorter time than traditional tooling because aluminum may be cut faster than other alloys.
Lower overall cost: Price is the 800 lb gorilla everyone would like to share. While Cold stamping molding aluminum costs more per pound than P20 along with other steel alloys, aluminum is much lighter hence the cost per pound usually is less overall cost. Aluminum is easier and faster to cut than steel; and, polishes faster, which reduces build time by weeks with substantial cost savings. Even hard coating aluminum will not increase the final expense of the tool significantly. Improved thermal conductivity cuts down process issues, with less scrap and faster cycle times, which decreases the overall per piece price. Then factor in less machine wear and less electrical costs because of improved efficiencies. Moreover, once the tool has stopped being needed, aluminum is definitely recycled.
In today’s economy and business climate every company that wishes to stay lean and competitive available on the market must think about the cost savings from aluminum tooling. Although there has been many improvements inside the grades of aluminum alloys, proper design, tooling and molding practices should be shown to truly reap the benefits of this alloy. In 35 years of aluminum tooling, the past five have already been the highest because of the attention that aluminum has finally been given. Like most successful innovations which can be born from the requirement to survive, aluminum tooling is not just the bridge to your faster product launch or maybe the cost benefits necessary for the planned budget; this is a successful alternative to steel tooling with huge benefits which will carry on and advance and influence the way forward for the plastics industry.