Abstract:
The objective of this work was to possibility study of NC and CNC machine retrofit.
According to survey results of a few factories, 4 NC and 1 CNC machines were found to be out of
order and left as a wreck. After completion the retrofit of the 3 machines and economical
analysis, it was found that firstly, the Hitachi cutting machine of model F7M was invested ฿
85,000, with the expected net income after retrofitting of ฿ 60,000 annually. The machine could
be used for 5 years with the present worth (PW) of ฿ 218,050 and internal rate of return (IRR) of
70.3% and payback period (PP) of 1.4 years. The overall equipment effectiveness (OEE) of the
machine increased from 92.1% before breaking down to 93.8%. Secondly, Okamoto NC grinding
machine of model PQM was invested of ฿ 46,700 with the net income after retrofitting of ฿
90,000 annually for a period of 5 years. The PW of ฿ 379,356, the IRR of 193.4% and the PP of
0.52 years were found. Also, the OEE was 90.0% which equal with before the retrofitting. Thirdly,
the NC drilling machine was invested of ฿ 91,000 with net income of ฿ 655,100 annually for a
period of 10 years. After retrofitting, the PW of ฿ 4,621,052, the IRR of 730.9% and the PP of
0.1 year were obtained. The OEE was increased from 95.6% to 96.1%. For the other NC lathe
Mori Seiki of model SL2 and CNC lathe Ocean of model GN3 were not appropriate to retrofit.
It is concluded that economical analysis should be done carefully before doing retrofit.