Economical Moulds are generally used in stamping production. This kind of mould is cost-effective and has high quality
. It requires special structures, materials and manufacturing methods.
In practical production, quality requirements on various sheet metal parts differ from each other. So do production volumes. In order to achieve the biggest technical and economic efficiency, some demands must be meet while some others have to be rejected. Manufacture of high quality products need the involvement of precise and complex moulds. This will increase cost of moulds and prolong production preparation cycle. Thus, if the demanded quantity is small, or the requirements for quality is low, quality of moulds should be lowered properly. Under this circumstance, lead-time should be shortened as the cost should be reduced. And then, structures of various economical moulds should be adopted into production.
First. Feasibility analysis on low-cost mould manufacture.
In order to realize low-cost manufacture of moulds, enterprises must think over three main technology-economy indexes: cost, cycle and quality. Moreover, the indexes should be considered from design, manufacture and application overall. The design should meet operating requirements and manufactural reliability. Manufacture must conform to design, while the technology adopted in production limits design. Application of moulds should in line with design and manufacture to work out suitable process program.
(1) Appling Synchronous Engineering (SE).
Stamping SE indicates that stamping craftsmen get involved in the design of moulds to eliminate faults and deficits in advance of production. This can shorten the development cycle of moulds.
(2) Laying down suitable process program.
A. Manufacturers should adopt special crafts such as hydraulic stretching, rubber bag stretching and so on to the best of their abilities. Therefore, several sets of moulds with different size can be diminished to only one set of moulds.
B. The production volume should also be taken into consideration for a small one can decrease cost and cycly of mould manufacture.
C. Using simple moulds such as low-melting alloy moulds, combination punching dies.
D. Comparing and analyzing every sort of accessories to realize combination moulds or one mould for several products.
(3) Have an eye on various factors that influence mould manufacture.
In general, factors like precision, surface treatment, surface roughness, numbers of holes and cavities, and heat treatment requirements and so on may all effects the quality of moulds. During the design process, requirements on precision, surface roughness and heat treatment should not be excessive, or it may increase unnecessary cost. Materials of mould manufacture can use recyclable low-melting alloy, polyurethane rubber, etc. Concerning the blanking dies, blanking clearance could be extended to reduce cost as long as they meet precision requirements.
(4) Apply advanced machining, electro-processing, chemical etching, etcetera into manufacture to replace or decrease workload of benching.
This can reduces demands on workers’ technological level in manufacturing operation. Moulds used in the past were relatively bigger. Hydraulic type moulds, for example, have complex surface with variable angles. When making this kind of moulds, workload of benching is extremely large. What’s more, these moulds require long lead-time but turn out to be of low quality.
Second. Common sheet metal parts and suitable moulds in aviation enterprises.
A large variety of sheet metal parts are used in this field. They are made into different shapes with assistance of diversified moulds
. Even the same kind of sheet metal accessory can also be made with several different moulds.
(1) Bending dies are the most complex one, compared with hydraulic dies, brake dies and drop-hammer dies. They are suitable for manufacturing large quantity of products. However, cost of them is high.
(2) Compound dies and progressive dies can make sure the precision of internal and external position when comparing with single process dies like punching dies and blanking dies. This two kind of moulds enjoy excellent production efficiency while the cost is high and lead-time is long. They are also suitable for manufacturing large quantity of products.
(3) Manufacture of trimming dies do not take comprehensively consideration of common features that exist among similar accessories. Therefore, more sets are needed in order to make complete products. Use of this sort of dies is low-efficient and expensive.
(4) Flanging dies are complex and expensive. They are not suggested to employ in small quantity of products. It is the same to bending dies and drawing dies.
(5) Drawing dies, especially those with multiple process, require large workload when doing mould test.
(6) Other type of moulds such as model tires, drop-hammer dies and rolling dies have low cost and suitable for manufacturing medium or small quantity of products. They can be applied in trial-manufacture of sheet metal accessories in airline enterprises. Thus, they belong to economical moulds.
In short, it is not easy to evaluate technology and economic efficiency of a process program for it concerning many factors. One should study special moulds and technology on base of general stamping technology and stamping dies, combing with actual production capacity, before making reasonable process programs and achieving the best technical and economic efficiency.