Myths have invariably been around: the globe is flat as well as the sun revolves around planet earth- to mention a few. The realm of manufacturing is no different with its own false beliefs. Today we have now the myth that aluminum tooling is “junk tooling or even for prototypes only”. This really is a stereotype which includes grown from earlier grades of Cold stamping molding aluminum that have been gummy, challenging to cut and improperly utilized in a manufacturing environment.
The development 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 grade of 7075 along with the ability to produce numerous 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 recently been done.
Cost factors are forcing manufacturers and major OEMs for taking a second look at aluminum. Way back in 1991 IBM did a five-year study on aluminum tooling with many different credible findings. Currently, Honda’s ongoing aluminum tooling study is actually a success and other companies are taking a renewed fascination with the cost savings that aluminum is offering. Unfortunately, old beliefs take time and effort to beat.
Aluminum can be used production volumes: The mistaken belief that only steel alloys including H-13, S-7, stainless steel or P20 steel must be used for production molds can be quite a costly one. An aluminum mold provides volumes between 100,000 approximately one thousand,000 components. This is a result of current aluminum grades which are heat treated as part of their creation process resulting in a 6 – 18RC hardness. Surface coating treatments can harden aluminum up to 56 – 62RC depending upon the procedure. When these hardness levels are in comparison 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 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 because of cold and warm spots inside 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 that are normally used with steel molds. Difficult-to-fill resins by using a high viscosity rate also reap the benefits of even heating as it reduces sheer stress upon the material by balancing the flow of material using a hot runner system. Glass-filled along with other abrasive resins could be run with success so long as additional care is taken to either hard coat or steel insert critical areas. Glass-filled resins may actually run better with aluminum due to its consistent thermal conductivity that assists in the flow of resin. PVC is usually incorrectly believed to be abrasive, when in fact it is actually corrosive. This is why 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 response to oxygen called aluminum oxide. The chromium in stainless-steel reacts much the same way to oxygen forming a layer called chromium oxide. A few of the newer grades of aluminum have chromium added for even greater corrosion resistance. You can find surface hardening processes that actually work well with PVC that can increase component output.
The term “production” is subjective, as Tropical type blister aluminum can achieve high volumes: So how exactly does “100,000 – 1,000,000 production-quality plastic parts” sound? Not really short-run or low-volume. For a lot of projects this can be more than enough for the entire project before the next design change or upgrade. Of course higher production quantities can be accomplished depending on the resin and design. Aluminum tooling can also be excellent for keeping marketplace share when bridge tooling is needed. Another benefit is when the tool every day life is exceeded, aluminum is forgiving as well as simple to preserve or enhance to obtain those last few plastic parts till the hardened steel production tool is prepared.
Unlimited surface finishes: Nearly every surface finish or texture that could be placed on a steel mold can be applied to an aluminum mold. Including Class A diamond finishes (SPI A-1), that are required for chrome plating. Certain grades of aluminum tend to be more suitable for this, which can also need a hard coating process to improve this finish. Bead blasting or any aesthetic texture finish can also be achieved with success.
Faster process cycles: As pointed out above, the thermal conductivity is actually a benefit that eliminates many processing issues. Fast and even air conditioning leads to less shrink and warpage issues from uneven heat dispersion. Less scrap can be a financial savings, but cycle times are also reduced by 30 percent on average, bringing down overall piece price. In order to run aluminum, a molder need to have good tooling practices and maintenance routines to improve the tool life and fully realize every one of the cost and time savings. This can include watching parting lines and shutoffs for wear to remove parts sticking and excessive wear. A sticking part can harm aluminum tools worse than steel. However, when the tool was built correctly and maintained to industry standards, it is really not a typical occurrence.
Design modification: Commonly, many projects inside the planning and design verification stages proceed through some kind of design modification. Aluminum could not really quicker to modify or groom for max efficiency when in the build or as soon as the tool is running parts, modifications to the initial design or to troubleshoot production issues are essential. Welding aluminum is becoming successful recently, allowing consideration even for cosmetic changes also.
No design restraints: Complex design geometries that require under cuts, which require mechanical slides, lifters or hand loads can be achieved exactly like in a steel mold. Careful project planning, a powerful knowledge of mold design, as well as experience in machining aluminum means there is not any reason to never expect aluminum to preserve dexjpky71 dimensions. Steel inserts can be used to further maintain critical areas for higher volume projects. This can all be carried out in a shorter time than traditional tooling because aluminum may be cut faster than other alloys.
Lower overall cost: Pricing is the 800 lb gorilla everyone would like to discuss. While Medical PCV sheet costs more per pound than P20 and also other steel alloys, aluminum is much lighter so the cost per pound usually is less as a whole cost. Aluminum is much easier and faster to reduce than steel; and, polishes faster, which reduces build time by weeks with substantial cost savings. Even hard coating aluminum will not add to the final cost of the tool significantly. Improved thermal conductivity decreases process issues, with less scrap and faster cycle times, which lessens the overall per piece price. Then factor in less machine wear and less electrical costs as a result of improved efficiencies. Moreover, when the tool is not needed, aluminum is definitely recycled.
In today’s economy and business climate every company that wants to stay lean and competitive in the market has to think about the fee savings from aluminum tooling. Although there were many improvements from the grades of aluminum alloys, proper design, tooling and molding practices need to be considered to truly make use of this alloy. In 35 years of aluminum tooling, the last five are already the highest due to attention that aluminum has finally been given. Like most successful innovations that happen to be born from the requirement to survive, aluminum tooling is not just the bridge to a faster product launch or maybe the cost benefits necessary for the planned budget; it really is a successful substitute for steel tooling with huge benefits which will carry on and advance and influence the way forward for the plastics industry.