One of important equipment in reforestation or tree planting is a pot for mulching tree saplings. Originally pots were made of clay but they were too strong. When the trees grow up the pots must be smashed in order to let the roots and the stems grow up. Plastic pots are a popular alternative to be potted tree saplings due to their longer usability flexibility keeping and easy cleaning. In addition they are light and easy to move or transport. Typical pots usually have holes at the bottom which make poor ventilation that caused the slow tree saplings growth. Pots with holes in the side let the air comfortably flow and the roots do not go to the bottom of the pot. When the pots are moved the tree sapling roots are not ragged this help reducing the mortality rate of tree saplings. To Construct and find out the efficiency of plastic pot injection molded with 7.7 cm. in size 8 cm. high 0.10 cm. thick and the weight of 20 grams in the specification form the work-piece can be injected. For Construction and finding out the efficiency of holes for putting the plastic pot injection molded with 41 cm. wide 51 cm.long0.20 cm. thick and the weight of 330 grams in the specification form every work piece can be injected. There are 18holes for putting the plastic pot and all 18 holes are in the same size. Asst. Prof. Prasong KanKaew

The shrinkage of plastic was caused by the shape of the product and the type of plastic used in the injection. The plastic shrinkage difference was resulted from the temperature used in melting the injection speed mold cooling and different injection surroundings. These led to unknown exact value of plastic shrinkage and the trial and error work has been done. As a result of trial and error work the injection products were not in the determined size. This research aims to find the percentage of plastic shrinkage according to standard test ASTM D955 from (Amorphous Thermoplastic) (Acrylonitrile Butadiene Styrene ABS). The findings showed that square specimen size 60x60x2 mm measured from vertical perpendicular to flowing direction the shrinkage was at 0.86% the shrinkage was at 0.59% when measured from flowing direction and the thickness expanded at 20%. For the rectangular specimen size 12.7x127x3.2 mm measured from vertical perpendicular to flowing direction the expanding was at 0.16% the shrinkage was at 0.88% when measured from flowing direction and the thickness expanded at 14.86%. The circular specimen size 100x3.2 mm the shrinkage was at 1.26 when measured from vertical perpendicular to flowing direction the shrinkage measured from flowing direction was at 0.82% and the thickness expanded at 13.23%

Bottle of poly propylene (Polypropylene: PP) to replace conventional non-conventional polycarbonate bottles. (Polycarbonate) are used as bottles and water bottles toys household goods which are BPA-contaminated and poly ethylene Terephthalic acid (Polyethylene. Terephthalate) PET water bottles juice bottles. Bottles And bottles and other drugs and chemicals have been canceled. Then turning to the bottle to PP because of the lightweight bottles float on water. Plastic and white The plastic safety can be reused many times (even used) in the UK has the plastic water bottles poly propylene and (Polypropylene: PP) to make water bottles so long but not as popular as bottle caps. open it (lid torn) bottle shape is beautiful with a little input. The process is a extrusion blow but from research using the dryer Injection blow (Stretch Blow) has studied the creation of injection molded preform 19 gram in order to blow a 500 ML size thickness. Preformed from 3.34 mm to 3.46 mm the average measured height of the preform from a mean of 70 mm measured at 69.88 m. m. the oldest of the preform. the average measured 25 mm and 24.96 mm is how a 500 ML size bottle blow molding blow molds percent discrepancy between the form specified. Average Percentage 0.0853 experimental results Blow the preform 19 gram of the injection can be molded into the bottle completely and can not be used as drinking water is due to the equipment used. blown trial Need to study next.

Material selection for mold making are not only material prices wages but also there are other factors such as thermal strength shine and resistance to temperature changing that caused distortion and cracks. Preform injection molding from Polyethylene Terephthalate (PET) consumes time for drying granulated plastic in 4 – 6 hours at 140 - 160°C and injects at 280 – 300 °C. This is a very high temperature to inject into mold at 10 – 15°C in cool area. The material for mold making must be able to resist to thermal shock. Today molding machines are made of grade P20 steel (Standard JIS) to produce preform that takes long cycle time due to poor cooling. The research aims to compare the pricing time in mold making to preform injection time that made of aluminum -A7075 grade and grade P20 steel. The experiment is to make a mold that made of aluminum A7075 grade and grade P20 steel injects 15 gram preform. The PET is used to blow into a blow mold with pressure at 30 – 35 bar (Two – Stage) that are 2 bottles of 350 ML. The results of material selection for preform mold making showed that aluminum A7075 grade is cheaper 27.04% the mold price is cheaper 23.6% and consumes less cycle time than grade P20 steel.

This research aims to study the shrinkage of plastic polyethylene Terephthalate used with the make blow mold in 2 stages. The shrinkage of work piece was determined in order to design the mold ; Z axis = 1% XY axis = 2.5% . The testing results were as follow. 1. Horizontal shrinkage(Z axis) was 0.85% which differed from the determined shrinkage(1%) at 0.15% 2. Vertical shrinkage(XY axis) was 1.83% that is 0.67% which differed from the determined shrinkage(2.5%) at 0.67%