“Automated Grinding Made Easy”

Monday, 19 September 2016

(Immediate Past Branch President Gareth Jermiah, Prof. MICME, presenting Chris Wilding of Omega Foundry Machinery Ltd, the award for the best paper presented during his presidential year.)

“Automated Grinding Made Easy”
Bob Sims of Sims Foundry Technologies

Branch President Ian Shergold, Prof. MICME, welcomed members and guests to this the first meeting of his Presidential year.

A minutes silence was held for Peter Wakeman, a long standing and very active member of the branch and branch council.

Immediate Past Branch President Gareth Jermiah, Prof. MICME, gave Chris Wilding of Omega Foundry Machinery Ltd. the award for the best paper presented during his presidential year.

Branch President Ian then introduced the speaker for the night, Bob Sims and his talk “Automated grinding made easy”.

Bob said in his introduction he would be talking about the Koyama automated grinding machine and its advantages for the foundry. Bob represents the Koyama automatic grinding machine through his company, Sims Foundry Technologies, and the machine is distributed throughout Europe by PS Auto Grinding Ltd of Cumbernauld.

There are many benefits to automated cutting and grinding of castings. The following are stated benefits for the Koyama machine.
a) Auto-fettling is generally 2 to 5 times faster than traditional hand fettling and on complex parts can be even faster than this.
b) The machine does not suffer from fatigue and is capable of a 23 hour production day.
c) Cutting and grinding in one operation is possible reducing time and often eliminating a need for a separate work station.
d) With a mechanical accuracy of 0.5mm and repeatability of
± 0.1mm a consistent quality of finish can be guaranteed.
e) The fettling process can be a considerable on-cost but automating the process will significantly reduce this. Less labour required per part, reduced footprint for the process and lower consumables all contribute and then the benefits of consistency just add to the cost savings. Savings in fettling cost are typically in the order of 50%
f) A fully enclosed cabinet with extraction keeps the operator away from harmful dust and noise and there is no exposure to hand arm vibration. This makes for a better working environment which also has added cost benefits for the company.
g) Having the fettling operation automated with its many benefits is a good marketing tool and indeed some end users will stipulate this for their products as the consistency and accuracy achieved can help reduce wastage further down the line.

The Koyama auto-grinding machine was developed by the Koyama Corporation, a leading Japanese foundry company. The machine was designed to address the problems of a production bottleneck, high labour costs, variable quality and health and safety issues. The first machine built in 1972 and operating in their foundry by 1973 was followed by several more but it was not until 1979 that the 1st machine was installed outside of its own facilities. Now there are over 3000 machines in operation worldwide.

Bob explained that he believed the success of the Koyama machine lies in the fact that it was developed by a foundry specifically for use in the foundry. From the outset the aim was to develop a machine that would be compact, keep the operators safe from the hazards associated with cutting and grinding, be simple to operate and simple to program. The machine makes use of diamond no wear technology which retains the accuracy of operation throughout the life of the grinding wheels which is said to be in the range 100,000 to 200,000 parts (grey or ductile iron). The wheels may be re-sharpened, if the backing disc is undamaged, at about 50% the cost of new.

For aluminium castings Bob explained that both the enclosure and cutting wheel have to be modified. The wheel is toothed rather than plain and whilst this addresses the problems associated with cutting aluminium the potential for teeth to break off creates another. Due to the high rotational speed of the wheels the enclosures have to be double skinned to ensure nothing can escape, such as a broken tooth, and put operators at risk from serious injury. Life of the grinding wheel (aluminium) is said to be in the range 2,000 to 10,000 parts

Machines come with 2 spindles, one for the 400mm wheel and a second for a small tool for the intricate work. It is now possible to add a third spindle as an option. The casting is secured in the fixture with a pneumatic adjustable clamp. There is a choice of 8 standard models of machine providing 6 different working envelopes. These then come with either single or twin tables for carrying the casting holding fixture(s).

Whilst there are several auto-grinding machines on the market Bob gave his view on why Koyama outsells all its competitors.
1) It was designed specifically for the foundry unlike many of the others which were adaptations of existing equipment.
2) Programming can be carried out by unskilled operators after as little as 2-3 days instruction.
3) The machine is free standing and can be installed and operating in just 1 day.
4) Programming is quick taking just a few hours making the system suitable for short and medium series production.
5) Holding fixtures do not need to be complicated and can be changed in as little as 4 minutes.
6) A patented tilting system for both the main wheel and small fettling tool means that with a well thought out holding fixture most if not all the fettling can be completed in one fast cycle.
7) A Conveyor system can be supplied which will remove swarf and larger pieces of metal from the cabinet.
8) Being totally enclosed removes the operator from harmful dust and noise and eliminates exposure to hand arm vibration injuries.
9) Many companies find that one operator can easily run 2 machines boosting productivity and profitability.
10) Payback on the investment is generally less than 2 years and looked after will continue to give good service for at least 15-20 years.

Bob illustrated his presentation with several videos which demonstrated the versatility and capability of the Koyama auto-grinder and then invited questions from the audience.

During the Q&A session the following points were raised:
I. Consumable costs (iron) are approximately 0.001p-0.005p per casting compared to 10p per casting by traditional fettling methods.
II. Whilst the Koyama is not currently suitable for grinding steel development is going ahead to address this
III. A range of standard tools are available but special tools can be produced as required.
IV. An upgrade to the processor is imminent.
V. Magnesium castings can be fettled but because of the fire risk the enclosure has to have fire detection and suppression using halon.
VI. Internal contours may require special tools before they can be fettled.

Branch president Ian gave a vote of thanks for an excellent lecture and then thanked PS Auto-Grinding for sponsoring the buffet.