## 4 Prototype for Experimental Evaluation
### Hardware Construction and Integration  
A hardware model of the prototype was constructed according to the conceptual design presented in Figures 10 and 11. Figure 12 shows the final setup of the constructed prototype, and the overall functional block diagram of the prototype is also shown in Figure 13. For the constructed mold/die clamping mechanism, its base plate, stationary platen, moving platen, tail stock platen, and most parts of link members were all made of JIS A6061 aluminum alloy, while its four tie bars were made of JIS SUJ2 bearing steel. Four flanged oil free bushings (made of bronze) attached to the moving platen were served as linear journal bearings when the moving platen translated relative to the tie bars. A flanged linear bashing attached to the tail stock platen was served as a linear ball bearing when the linear shaft of the input link (made of JIS SUJ2 bearing steel) translated relative to the tail stock platen. The link members were connected by precision pivot pins (made of JIS SUS304 stainless steel) to form all revolute joints with sliding fits [29] in the linkage assembly. For the length adjustable link member, its two linear shafts were made of JIS SUJ2 bearing steel, and its four clamping shaft collars and compound screw were all made of JIS SUS304 stainless steel. The actual lengths of all link members, except the length adjustable one, had been measured by using a Giddings & Lewis Sheffield Measurement Cordax RS-25 coordinate measuring machine (CMM) before they were assembled together. As a result, the length errors of the measured link members were, in average, distributed within a small range of \(\pm\)0.025 mm.  
Subsequently, the ballscrew linear table was driven by a precision ballscrew mechanism (with an accuracy class of C5 and a lead of 5 mm) coupled with an Oriental Motor PKE955 BC five-phase stepping motor and an Oriental Motor RKSD507-A five-phase stepping motor driver. The stepping motor module was set to an angular resolution of 25,000 steps/rev, that is, a fine linear displacement of 0.2 \(\upmu\)m per step could be achieved. A Renishaw RGH41X/RGS40S optical linear encoder that has a resolution of 1 \(\upmu\)m was used to detect the resultant output position (of the moving platen). A Nippon Tokushu Sokki (NTS) LRM-500N load cell, which has a measuring range of \(\pm\)500 N, coupled with an Algol Instrument AL-168 signal amplifier were used to detect the required input force for driving the entire constructed mechanism.  
Figure 11: Explosive view of the CAD model of the length adjustable link member.  
control card embedded in the host PC was used to manipulate the stepping motor and to receive the positional signals detected by the optical linear encoder through its I/O ports. Moreover, the force signals detected by the load cell/signal amplifier were received through a National Instrument (NI) USB-6000 data acquisition (DAQ) device connected to the host PC through its universal serial bus (USB) port. In addition, the required human machine interface software and also motion control and force measuring programs were developed and integrated in the NI LabVIEW environment.