Fabrication of Porous Hydroxyapatite through Combination of Sacrificial Template and Direct Foaming Techniques

The porous hydroxyapatite (HA) bioceramics were prepared through combination of sacrificial template and direct foaming techniques using PMMA granules (varied from 5 to 50 wt% in content) as a template and H2O2 solution (varied from 5 to 30 wt% in concentration) as a foaming agent, respectively. The effects of PMMA content and H2O2 concentration on final porosity, microstructure and mechanical strengths were studied. The porous samples using PMMA provided the porosity ranging from 52% to 75%, the samples using H2O2 had the porosity ranging from 82% to 85%, and the sample using both pore formers provided the porosity ranging between 84% and 90%. The higher content of PMMA and concentration of H2O2 led the porosity increased, leading to a decrease in the compressive and flexural strengths. Furthermore, this combination technique allowed interconnected pores having two levels of pore size, which were come from PMMA and H2O2. The PMMA formed the small pores with the diameter ranging between 100 and 300 μm, while H2O2 provided the larger pores with the diameter ranging from 100 to 1,000 μm depending on concentration

Factors Affecting the Mechanical Properties Variation after Annealing Of Cold Rolled Steel Sheet

Cold rolled steel industry in type of batch annealing furnace, the mechanical properties of steel sheet have variation by each position. The parameters of annealing temperature and time were analysed to work out the source of mechanical properties variation. This experiment is using low-carbon steel sheet that were cold rolled at the same reduction ratio. Then annealed applying by different annealing temperature and soaking time in laboratory furnace. The mechanical properties which were examined. Yield strength, Tensile strength, %Elongation and Hardness. The result showed that (1) Increasing the annealing temperature could remarkably decrease the yield strength, tensile strength and hardness, whereas the %Elongation could be increased. (2) Increasing the soaking time could slightly effect on mechanical properties. (3) The annealing temperature of 650°C with soaking time of 2 hr should be applied to provide the mechanical properties close to target value (4) Grain size of the workpieces trended to be grown from the annealing temperature of 610°C.The experiment it can be concluded that annealing temperature and soaking time have significant effect on the mechanical properties variation in batch annealing

Reduction of adhesive stain defect in flexible printed circuit board on hot pressing process: A case study of electronic component factory

The objective of this research is a reduction of an adhesive stain defect in flexible printed circuit board in hot pressing process, the electronic factory. The manufacturing have been processing by sheet type of products with ninety-six pieces of flexible printed circuit boards. Causes of the problem include the before and internal hot pressing process. In process beginning times, the most right row of products between the cooling plate and the hot pressing machine has temperature 71.2◦C that is higher than glass transition temperature (Tg) 60◦C. Those products’ temperature lead to evaporate a polyimide adhesive before hot pressing process beginning. The internal hot pressing process include the preheat times and the pressure time. In the preheat time the problem is a gap between lower and upper plate, was under specification (Under 1 mm) and leaded to adhesive polyimide stain. In the actuality this time requires temperature and low pressure that mean a gap within 1 – 2 mm (between lower and upper plate). In pressure times the hot pressing plate surface is not flat and products are pressed by insufficient force that it lead to generate an adhesive stain on flexible printed circuit boards. That force is measured by the pre-scale paper and a result, RGB color, is provided. And then color density (From standard color sample) and RGB color (From pre-scale paper) is found out the relation by Photoshop program and multiple regression theory using. The formula is applied to compare with defect so as to find out the suitable color density (Defects reducing). The solving solutions is provided including the gap reduced adjustment between cooling plate and hot pressing machine before hot pressing process, the plate adjustment within specification in the preheat time and the pressing plate polishing in the pressure time. Results of study and solving are provide defect reduction from 24.4 percentage to 7.2 percentage of total study product

Reduction of adhesive stain defect in flexible printed circuit board on hot pressing process: a case study of electronic component factory

The objective of this research is a reduction of an adhesive stain defect in flexible printed circuit board in hot pressing process, the electronic factory. The manufacturing have been processing by sheet type of products with ninety-six pieces of flexible printed circuit boards. Causes of the problem include the before and internal hot pressing process. In process beginning times, the most right row of products between the cooling plate and the hot pressing machine has temperature 71.2◦C that is higher than glass transition temperature (Tg) 60◦C. Those products’ temperature lead to evaporate a polyimide adhesive before hot pressing process beginning. The internal hot pressing process include the preheat times and the pressure time. In the preheat time the problem is a gap between lower and upper plate, was under specification(Under 1 mm) and leaded to adhesive polyimide stain. In the actuality this time requires temperature and low pressure that mean a gap within 1 – 2 mm (between lower and upper plate). In pressure times the hot pressing plate surface is not flat and products are pressed by insufficient force that it lead to generate an adhesive stain on flexible printed circuit boards. That force is measured by the pre-scale paper and a result, RGB color, is provided. And then color density (From standard color sample) and RGB color (From pre-scale paper) is found out the relation by Photoshop program and multiple regression theory using. The formula is applied to compare with defect so as to find out the suitable color density (Defects reducing). The solving solutions is provided including the gap reduced adjustment between cooling plate and hot pressing machine before hot pressing process, the plate adjustment within specification in the preheat time and the pressing plate polishing in the pressure time. Results of study and solving are provide defect reduction from 24.4 percentage to 7.2 percentage of total study product

Factors Affecting the Mechanical Properties Variation after Annealing Of Cold Rolled Steel Sheet

Cold rolled steel industry in type of batch annealing furnace, the mechanical properties of steel sheet have variation by each position. The parameters of annealing temperature and time were analysed to work out the source of mechanical properties variation. This experiment is using low-carbon steel sheet that were cold rolled at the same reduction ratio. Then annealed applying by different annealing temperature and soaking time in laboratory furnace. The mechanical properties which were examined. Yield strength, Tensile strength, %Elongation and Hardness. The result showed that (1) Increasing the annealing temperature could remarkably decrease the yield strength, tensile strength and hardness, whereas the %Elongation could be increased. (2) Increasing the soaking time could slightly effect on mechanical properties. (3) The annealing temperature of 650°C with soaking time of 2 hr should be applied to provide the mechanical properties close to target value (4) Grain size of the workpieces trended to be grown from the annealing temperature of 610°C.The experiment it can be concluded that annealing temperature and soaking time have significant effect on the mechanical properties variation in batch annealing

Investigations of spherical grinding parameters on circularity error, finished diameter, and grinding forces for porous polyurethane foam

The aim of this study was to examine the effect of grinding variables on the circularity error, finished diameter, andgrinding forces of porous polyurethane foam (PPUF). A cube of PPUF having the size of 21 mm was transformed into a roundshape using a vertical wheel grinding with the circular groove pad developed. The grinding speed (Vs) of the wheel wasvaried between 1.41 and 5.18 m/s. The cross head speed of the circular groove pad (f) was controlled at 1, 3, 5 mm/min. Theabrasive grit size (A) of 20 and 53 μm made of silicon carbide were applied. Two replications of experiment were randomlyperformed. Diameter and circularity error of the ground specimen were determined by vision measuring machine. The tangentialand normal forces of grinding were obtained using a dynamometer. The experimental data were statistically analyzed. The study found that (1) the grinding speed could remarkably affect the circularity error, finished diameter, and grinding forces,(2) the grinding speed ranged between 2.83 and 3.77 m/s could contribute to sphere shape specimens, and (3) the grinding speed of 3.30 m/s, cross head speed of 1 mm/min, and abrasive grit size of 20 μm provided the least circularity error

Cutter usage management for rubberwood furniture part machining process

The objective of this research work was to improve cutter usage management of a vertical-shaft cutting machine for rubberwood furniture industry. The milling cutter used consists of six-straight teeth mounted on the vertical-shaft of a milling machine. A pre-cut rubberwood specimen had the height of 40 mm and outer curve length of 330 mm. The steps of study were (1) studying the current cutter usage management of a factory through studying the important factors of current manually cutting such as specimen feed, cut depth, and cutting speed. (2) Developing the process for improvement of cutter usage management via studying sanding time and roughness after sanding with the coarse and fine size grits of sand paper number 100 and 180, respectively which the furniture factories normally apply; setting-up the surface roughness requirement for a cut-part application; studying a suitable cutting condition for part machining by controlling the cutting factors, and also determining the tool life that provided the cut-surface roughness equivalent to the roughness sanded by the sand paper number 100; and finally, developing the method for improvement.The study found that (1) the specimen feed had a significant effect on tool life. The higher feed caused a decreased tool life and an increased cut surface roughness; (2) the cutter was used to cut the specimen until the cut surface of specimen was torn grain or specimen could not be machined. Consequently, all the cut specimens had to be sanded by coarse and fine sanding, and the total time was 16.2 sec/piece; and (3) the method developed was setting the tool life which was equal to the accumulated machining time performing the cut-surface roughness of 8 μm equivalent to the roughness sanded by using the size grit number of 100. It could eliminate coarse sanding operation. Therefore, the total sanding time remarkably decreased from the existing 16.2 sec/piece to 6.1 sec/piece or 62.2 % reduction of existing time