Myths have invariably been around: the planet is flat as well as the sun involves our planet- to name a few. The field of manufacturing is no different with its own false beliefs. Today we now have the myth that aluminum tooling is “junk tooling or even for prototypes only”. This really is a stereotype containing grown from earlier grades of Medical PCV sheet that had been gummy, hard to cut and improperly found in a manufacturing environment.
The growth 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 caliber of 7075 as well as the capability to produce countless parts. However, many manufacturers failed to follow his recommendations. Instead, many select the wrong aluminum alloy and did not follow good tooling practices. Unfortunately, damages to aluminum’s reputation had been done.
Cost factors are forcing manufacturers and major OEMs to take another look at aluminum. Back in 1991 IBM did a five-year study on aluminum tooling with a lot of credible findings. Currently, Honda’s ongoing aluminum tooling study is actually a success as well as other companies are taking a renewed interest in the cost savings that aluminum has to offer. Unfortunately, old beliefs are hard to overcome.
Aluminum can be used as production volumes: The mistaken belief that only steel alloys like H-13, S-7, stainless steel or P20 steel ought to be utilized for production molds might be a costly one. An aluminum mold offers volumes between 100,000 up to one thousand,000 components. This is a result of current aluminum grades which are heat treated as part of their creation process causing a 6 – 18RC hardness. Surface coating treatments can harden aluminum up to 56 – 62RC depending on the process. When these hardness levels are compared to 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 can be used on aluminum: Aluminum’s excellent thermal conductivity allows resins to circulate more evenly than steel. Certain resins like clear acrylics and polycarbonates often times have processing issues due to hot and cold spots inside a mold. Aluminum’s even heat dispersion reduces these areas resolving bubble as well as other aesthetic issues. Other high-temperature resins can run successfully in aluminum with cartridge heaters that are normally combined with steel molds. Difficult-to-fill resins having a high viscosity rate also take advantage of even heating since it reduces sheer stress upon the content by balancing the flow of material using a hot runner system. Glass-filled and other abrasive resins may be run with success as long as special care is delivered to either hard coat or steel insert critical areas. Glass-filled resins may actually run better with aluminum because of its consistent thermal conductivity that assists from the flow of resin. PVC is frequently incorrectly thought to be abrasive, when in fact it is actually corrosive. This is why stainless-steel alloys are chosen over P20. Both stainless-steel and aluminum are corrosion-resistant naturally. Aluminum forms a .000001 (microinch) self-healing layer like a reaction to oxygen called aluminum oxide. The chromium in stainless steel reacts the same way to oxygen forming a layer called chromium oxide. A few of the newer grades of aluminum have chromium added even for greater corrosion resistance. You will find surface hardening processes that really work well with PVC that could increase component output.
The phrase “production” is subjective, as Medical PCV sheet can achieve high volumes: So how exactly does “100,000 – 1,000,000 production-quality plastic parts” sound? Not quite short-run or low-volume. For most projects this is ample for the entire project till the next design change or upgrade. Obviously higher production quantities can be accomplished depending on the resin and design. Aluminum tooling can also be ideal for keeping marketplace share when bridge tooling is necessary. An added benefit is when the tool life is exceeded, aluminum is forgiving and straightforward to preserve or enhance to get those last few plastic parts before the hardened steel production tool is prepared.
Unlimited surface finishes: Nearly every surface finish or texture that could be put on a steel mold does apply for an aluminum mold. Including Class A diamond finishes (SPI A-1), that happen to be required for chrome plating. Certain grades of aluminum are definitely more ideal for this, which might also call for a hard coating process to further improve this finish. Bead blasting or any aesthetic texture finish may also be achieved with success.
Faster process cycles: As stated before, the thermal conductivity can be a benefit that eliminates many processing issues. Fast and even heating and air conditioning brings about less shrink and warpage issues from uneven heat dispersion. Less scrap is a cost savings, but cycle times may also be reduced by 30 percent normally, bringing down overall piece price. In order to run aluminum, a molder will be needing good tooling practices and maintenance routines to improve the tool life and fully realize all of the cost and time savings. This consists of watching parting lines and shutoffs for wear to get rid of parts sticking and excessive wear. A sticking part may damage aluminum tools worse than steel. However, if the tool was built correctly and maintained to industry standards, it is not necessarily a frequent occurrence.
Design modification: Commonly, many projects from the planning and design verification stages experience some sort of design modification. Aluminum could stop being much easier to modify or groom for maximum efficiency when throughout the build or when the tool is running parts, modifications for the initial design or even to troubleshoot production issues are necessary. Welding aluminum has become successful recently, allowing consideration for even cosmetic changes too.
No design restraints: Complex design geometries that need under cuts, which require mechanical slides, lifters or hand loads can be achieved much like inside a steel mold. Careful project planning, a robust understanding of mold design, along with expertise in machining aluminum means there is absolutely no reason not to expect aluminum to maintain dexjpky71 dimensions. Steel inserts may be used to further maintain critical areas for higher volume projects. This may all be accomplished in less time than traditional tooling because aluminum could be cut faster than other alloys.
Lower overall cost: Expense is the 800 lb gorilla we all want to talk about. While Medical PCV sheet costs more per pound than P20 as well as other steel alloys, aluminum is lighter in weight and so the cost per pound usually is less altogether cost. Aluminum is easier and faster to slice than steel; and, polishes faster, which reduces build time by weeks with substantial financial savings. Even hard coating aluminum does not enhance the final price of the tool significantly. Improved thermal conductivity cuts down process issues, with less scrap and faster cycle times, which lessens the overall per piece price. Then consider less machine wear and fewer electrical costs due to improved efficiencies. Moreover, when the tool has stopped being needed, aluminum is readily recycled.
In today’s economy and business climate every company that would like to stay lean and competitive in the industry needs to consider the price savings from aluminum tooling. Although there were many improvements within the grades of aluminum alloys, proper design, tooling and molding practices need to be shown to truly make use of this alloy. In 35 several years of aluminum tooling, the last five are already the most notable as a result of attention that aluminum has finally been given. Similar to most successful innovations which are born from the desire to survive, aluminum tooling is not just the bridge to your faster product launch or maybe the cost savings needed for the planned budget; this is a successful replacement for steel tooling with huge benefits that can continue to advance and influence the future of the plastics industry.