CONCLUSIONS FOR THE DEVELOPMENT OF RAPID TOOL
MANUFACTURE APPROPRIATE TO THE NEW ZEALAND 1 28
MANUFACTURING ENVIRONMENT
8 . 1 Introduction 129
8.2 Conclusion 129
8.2. 1 Identification of customer needs 129
8.2. 2 Design 130
8.2. 3 Selection oj materials 1 30
8.2. 4 Integration between conventional and modem machinery 1 3 1
8.2.5 Use of established formulae for PR and SR 1 3 1
8.2. 6 Co-ordination between the marrujactures and academic
institutions 1 3 1
8.2. 7 Establishment of an Industrial development organisation 132
8.2. 8 Encouragement ojjoint venture collaborations 1 32
This chapter describes the author's conclusions for the development of rapid tool
8.1 Introduction
According to 199511996 Statistics published by the Economist intelligence unit, the manufacturing sector contributed 1 8.6% of the total real GDP to the NZ economy. Also it gained 62.5% of the total export market of the country. Under these circumstances according to the strength, weakness, opportunities and threats (SWOT) analysis which was carried out by the manufacturing advisory group, there are some important points for manufacturing technologists should look at. Inadequate knowledge and resources for global market development is one of our weaknesses among others. Widening education gap between New Zealand and competitors is also a serious threat. Therefore it is very necessary to train and educate manufacturers in order to meet these challenges. In selecting manufacturers, it is vital to identify the importance of small and medium scale manufacturers. They are a source of renewal and future growth, generally highly motivated and innovative and finally make a particular contribution to employment.
Most of the plastic injection moulding tool makers and plastic manufacturers here in New Zealand are small or medium scale manufacturers. However they encounter
specific difficulties in maintaining the funding for further improvements, information on market opportunities, technology and other key business matters which are essential for them to achieve a satisfactory growth.
Hence based on studies and experiments already discussed in earlier chapters, the author makes following conclusions in order to improve the quality and effectiveness of injection moulding tool manufacturers.
8.2 Conclusions
8.2.1 Identification of the customer needs
Tool makers are usually involved before the product suits the market, so those factors are less important. Usually it is just tight deadlines that is the problem. Tool makers need and usually get, very good information from the customer. After consideration about the quality, quantity, how quickly the customer needs the said item manufacturer can decide the design, choose the material and the method of
manufacture of the injection moulding tool.
8.2.2 Design
Before manufacturing the mould, plastic part has to be designed. Depending on the plastic material which is used to produce the part, thickness of various sections, height and other dimensions can be detennined using modern commercially available
software such as Cad mould, Mould flow, Cad form etc.. In addition to
determination of part dimensions, it is possible to determine optimum dimensions of runners, gates, sprues etc., and the location of the sprue. Also using these software packages, the mould can be designed for optimum cooling, moulding filling without weld lines etc .. Further, the mould has to be designed to withstand forces such as compression, tensile etc. while it is in operation. This can be carried out by using commercially available software such as 'Mystro', a finite element analysis programme.
Usually most manufactures do not carry out either flow or force analysis. They over
design and select higher dimensions than required. This means waste of money, time and skills. By implementing a proper design procedure using modern software material, money and time can be saved. Also this improves the quality of the end product greatly.
8.2.3 Selection of material
As discussed in the section 8.2. I, if the plastic manufacturer want to produce large quantities over a very long duration, material such as mould steel can be selected. Alternatively Mild Steel can be used with tool steel inserts. Aluminium is a very good material for manufacture of moulds. Use of Aluminium must be encouraged for injection moulding tools. As per discussion about mould materials, Zinc is an another important alternative material for rapid manufacture of moulding tools. All these
materials except mould steels are easily machinable and easy to handle. Hence
according to the required quality, quantity, the urgency of the requirement of the finished tool, correct mould material must be selected and used. Relative cost of
these materials is attached in Appendix M.
In addition to that, selection of pre manufactured mould component such as mould bases, guiding pins and bushes, ejector pins etc. is an another possibility.
8.2.4 Integration between conventional and modem machinery
As conventional machinery such as centre lathes, drilling machines, surface grinders etc., still plays a vital roll in mould tool manufacture, these cannot be discarded. Also, it is not possible for every manufacturer to use modern machinery due to heavy capital investment, lack of trained personnel etc . . Therefore it is necessary to have integration between conventional and modem machinery.
8.2.5 Use of established formulae for PR and �
Since fonnulae, have already been established for rate of penetration and surface quality in EDM operation, these can be used in rapid manufacture of injection
moulding tools in order to increase productivity and quality.
After determining the final surface roughness required, values for TON and I can be
decided. Since there is
a
relationship for I and TON, TOFF and Ip values for TOFF and Ipcan be decided to suit the formula. For accurate calculations, estimated I should be used by using graph actual I vs estimated I in figure 7. 1 . Since values of LToN and T OFF have been decided, PR can be determined.
Therefore, for required depth of cut the machining time can be determined. Hence, proper costing procedure and planning all jobs in the tool room for required time frame.
Further, according to the experimental findings, surface finish can be further improved by increasing the jump set and reducing TON and Ip. Therefore when the tool reaches to the final depth of cut, the machinist can change parameters in order to increase the surface finish. By this, surface quality can be further improved with out affecting the PR. Also this reduces the final mould polishing time.
8.2.6 Co-ordination between the manufactures and academic institutions
As mentioned in the section 8 .2.3, since the capital investment for CNC machinery and CAD/CAM software is high, small and medium manufacturers should be encouraged to get the help from universities and polytechnics throughout the country. Since the universities and technical colleges have machinery, software packages and personnel who are knowledgeable about the use of software packages, programming etc., it is easier and cheaper for manufacturer to use these facilities. In addition to that, Author concludes that, it would be beneficial if the universities can
orgaruse short courses in rapid injection mould tool manufacture for small and medium scale manufacturers who are in the industry. Further according to the author's thinking, these short courses, workshops and seminars can be organised by universities funded by the business development board, New Zealand.
8.2.7 Establishment of Industrial development organisation
Further, author thinks that, it is advantageous to establish an organisation for industrial development by the government of New Zealand which may have branches
through out the country in order to help all small and medium scale manufacturers.
This will help all manufacturers
who
are engaged in the plastics as well as other industries.8.2.8 Encouragement of joint venture collaborations
Finally manufacturers engaged in moulding tool manufacture, (as well as other sectors in manufacturing) must be encouraged to have joint venture collaborations with manufacturers both in New Zealand and other industrially developed countries
Required End Product