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From old tooling to Al tooling the role of second generation moulds
The manufacturing industry, especially the one tied to plastic products, currently finds itself operating in a global and extremely competitive market, where the key factors of success are more and more linked to the ability to:
- reduce product development time (time-to-market)
- increase their variety (innovation, re-design)
- reduce costs (cost competitiveness)
The II Generation Mould is able to offer valid solutions to all these problems.
By II Generation Mould or Flexible Mould we mean an Aluminium mould which is no longer designed only to create prototypes through the use of NC machines, injection presses and generic (or old concept) Al alloys, but intended to redefine a modern and flexible industrial cycle, which unites HSM machines and NC presses and selected Al alloys.
In other words, aimed at creating the passage from "Old Tooling" to "Al Tooling".
In the context described above, and with reference to flexibility as a key element for the success of businesses, the II Generation Aluminium Mould can offer greater flexibility in many ways:
 Financial-management flexibility: advantages in terms of high project "manageability", referred also to complex industrial programmes.
Design flexibility: advantages in the planning and design phase of the new product and its mould.
Technological-productive flexibility: advantages in the passage "mould test —> beginning of current model production".
Testing flexibility: vantaggi nel passaggio "test stampo —> inizio produzione di serie".
Moulding flexibility: advantages during permanent operation (even when producing large series).
Financial/management flexibility
When constructing a single mould, it is quite rare and - even if in the individual case the advantages, such as manufacturing time and workshop cost savings, are indeed measurable - the economic advantages may not be a determining thrust to making strategic choices such as "Old Tooling —> Aluminium Tooling".
Vice versa, when constructing entire families of moulds for a given product (a new motorcycle, a new car, a new electrical appliance) the overall capital immobilised in tooling is quite different when passing from a complete set of steel moulds (old tooling) to a series of Al moulds (Al Tooling).
If we add that the return on this capital will begin only when the last mould has been finished and only when the product - complete in all its parts - will be sellable, the important advantage of the Al alloy mould - which requires decidedly reduced construction time and costs - becomes very clear.
Advantages such as fixed cost management and flexibility-amortisation will of course increase with the number and size of the moulds.
2. Design flexibility
With the use of Aluminium Tooling it is possible to construct moulds with designs considered extreme for various reasons:
- either because the parts are very complex and manufacturing starting with steel would prove to be definitely anti-economical (see walls thicker than 5 mm with difficult cooling or delicate electroerosion operations performed directly on Al moulds with a milling machine).
- or because the parts are of considerable size (use of 2,200 by 1,000 raw blocks with 600 or even 700 mm thickness)
- or because it is necessary to turn an idea or a sketch into a mould for thermoplastic material in an extremely short amount of time.
3. Technological-productive flexibility
Here the advantages are so numerous that it is only possible to outline them:
- perfect characteristics of selected Al alloys, and especially 7000 alloys, for High Speed Milling (without making it necessary to change the cutting tools).
- consumption of the small plates made of sintered hard materials (Sintered Carbides) and HSS and SHSS tools, will tend towards zero, (compared with steel working).
- almost total elimination of slow processes, such as electroerosion (EDM).
- definite simplification of "machining shop" equipment (only or mainly milling equipment).
- actual (without interruption) high-speed milling (HSM).
- and in general, a considerable increase in the preparation speed of the milled mould.
- advantages in terms of construction speed, which will be more considerable the larger the mould size and the greater the amount to be removed by milling (construction of "huge moulds").
- easy solution of cooling problems and related circuits, whereas this is impossible for many types of steel (steel used for moulds that are more and more "insulating").
- drastic reduction of fitting time (as a consequence of the lower bending stress induced in the mill-chuck-spindle carrier system by the Al mould).
- drastic reduction of the time required for polishing, be it manual or HSM.
4. Testing flexibility...
up to the replacement, in some cases, of Rapid Prototyping
Once the 'mathematics' of the product to be moulded, i.e. drawings on computer support, are available, the construction speed of an Al alloy mould may be less than two weeks and in many cases even less than one.
Once the mould is finished - if the workshop is organised to handle the fast/full cycle with the injection presses available - the tool can immediately be put to use in the fastest process for creating thermoplastic parts: injection.
It is obvious that no layer by layer addition or subsequent layer sintering process (normal Rapid Prototyping processes) can compete with the obtainment of "one shot" parts with a single injection; especially as the part is made of the final thermoplastic material. Use of the plastic material of the final component is often quite difficult - if not impossible - with traditional R.P. systems.
If the first injected part satisfactorily passes the size test, all the following parts will be nothing but the immediate repetition of the first "shot".
5. Moulding flexibility
During the production phase, the flexible mould features a number of performance characteristics with which it is practically impossible to compete.
In fact the light weight of the Al mould:
- allows a clear reduction of idle time for changing moulds
- simplifies "shape change" on the presses and - consequently - the easy installation on the press facilitates the beginning of the moulding cycle
- does not require oversized runways, pillars and foundations or oversized lifting equipment
- makes possible (as a consequence of the flexibility elements mentioned above) thermoplastic mould production in light and pre-existing industrial sheds
While the extremely high thermal conductivity (from 5 to 8 times that of steel):
- allows the achievement of even higher moulding rhythms (record values on new presses), thus reducing process time by 30 / 40% compared to steel, and especially types of mould steel that are more and more insulating or in any case feature poor thermal conductivity
- · in the case of greater thickness (s) of the thermoplastic material (i.e. with s > 3 mm or especially > 5 mm), the high conductivity of the aluminium alloys becomes an off —> on condition; this regards parts that are practically impossible to mould with steel tools.
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From Old Tooling 