Thailand is a well known country where jewelry is produced to export. The process of jewelry production needs many special skills and efficient machines. Moreover the preparation of plaster is also important in producing jewelry. This requires various stages and takes more time to do. However these problems can be eliminated by knowledge in engineering. Therefore this study aimed to develop the vacuum mixer for mixing Investment for jewelry production. The vacuum mixer consists of 12 Hp 220 volts ac electric motor with the gear which has 1:40 dimension. The whole body of the vacuum mixer is made of stainless steel. The pot for mixing the Investment is 21 em. wide and 31.5 em. high. The tub at the base for placing the pot is 29 em. wide and 21 em. high. This base is equipped with a 20 m3 per hour vacuum ventilator and a vibrating motor. This vacuum mixer is operated by the electric motor which transmits power into gear. Then the gears drive the belt to make the blade stiring the Investment and water in the pot until they are well mixed together. Then the mixture is forced to the tub at the base by the valve while the air is sucked up and the mixture of the Investment is cured until all bubbles are disappeared from the mixture. After experimenting the result revealed that the use of the vacuum mixer can reduce the steps in preparing the plaster from 8 steps to 4 steps. It can also save 52% of time allotted.

The purposes of the research were to create and efficiency validation of computer assisted for the courses of practiced to make body of ornaments based standard 90/90 and analyse the leaning achievement of the student after by using computer assisted instruction. The subjects in the study were 17 first year diploma students enrolled in Rajamangala University of Technology Phra Nakhon. The Researcher using the experiment by let the students do until test before class And then study by using computer assisted instruction focused on practiced to basic turning. After that let students do the unit test again at the class and calculate to find out the efficiency of the computer assisted instruction and analyse the leaning achievement of students after study. The research result revealed that the efficiency of the computer assisted Instruction was efficient in standard 90/90 Moreover after learning achievement At significant level of 0.05

Product development of End Mills AISI M42 tool steels products by cryogenics treatments after process by heating system through austenite structure had been conducted in order to increase effectiveness of wear resistance geometry designed in quenching figures quality of chip flow and improved by the cutting edge with sub-zero and heating system through producing the cutting tools on the rim of rake angle at 8° and 12° and 15° austenite temperature at 1210 ° C varied in room with temperatures at 35°C lower - 70 °C and -196°C respectively. The tempering at 535°C had been three time. End Mills figures then had been operated by 5 axis CNC grinding machine for the tools. The experiment had been conducted in accordance with the AISI 1045. Such as result revealed that stress relive of tools. it hardness between 67.7 up to 68.3 HRC and reduced I HRC. Having compared with the un-stress relief it revealed that on the 15° rake angle shear force increased 8° and 12° respectively. The result had denied the Shear theory however resisted against erosion better than 12° and 8°. The result revealed that cooling at - 196°C would help increase more 15% of cut effectiveness. Cooling treatment below 0° had tended to positively resist the erosion of the out tools. With its development of control of degrees of cooling substance acid the quality of products would be better increased. Such a result could be based of the development of product lines on highly-qualities cut tools which was domestically produced.

The purposes of the research were to create computer assisted intruction for Manufacturing process subject to find out the efficency validtion of computer assisted instruction based on the standard of 90/90 and to analyse the students learning achievament after using the computer assisted instrucion. The subjects the study were 17 first-year diploma enploma engineering students enrollong at Rajamangala University of Technology Phra Nakhon. The researcher made the experiment by having the students pretest. The they studied by using the computer assisted instruction foused on practiocing basic turning. After the students had studied and had posttest the efficency of the computer assisted instruction was calculated as well as leaning achievement was analysed. The research resilt revealed that the efficiency of the computer assisted instruction was at the standard of 90/90. Morever the learning achivement after using the computer assisted instruction was different at the singificant lavel of 0.05

Blends of R22/R152a/R124 have been proposed to replace R12 in refrigeration systems.In this research work a technique to simply evaluate thermodynamic properties of refrigerant mixtures has been developed from Raoults Law.the method has been approached to evaluate the properties of the refrigerant blends avalable in the market such as MP39( R22/R152/R124 53/13/34)MP52 (R22/R152a/R124 33/15/52)and MP66 (R22/R152/R124 61/11/28) .The results agree well with those given by the manufacture within 5 % error The method has also been used to evaluate the properties of the ( R32/R125/R134a 23/25/52)refrigerant agree wall with those given from the manufacture with in 3 % error The thermodynamic property dlagrams of these refrigerant blends are also proposed.