The hole expansion process is a forming process that the fracture easily occurred on the hole edge. Therefore, many research papers presented various processes to make a precision pre-hole shearing to a hole expansion process such as wire cut, EDM, and laser cut. The purpose of this work is to increase a hole expansion ratio on the high strength steel sheet. The conventional piercing by piercing punch and piercing with a counter punch was used to make a pre-hole shearing process in this research paper. The high strength steel grade 590 and 980 MPa of 1.2 mm of thickness were used in the experiments. From experimental results, it was found that the pre-hole shearing by piercing with a counter punch can be increased a shear surface on cutting edge of workpiece. Moreover, the used piercing with counter punch can improve the hole expansion ratio more than the conventional piercing process because sheared surface around the hole edge was increased.

The enormous coconut shell waste from local farmers and manufacturers has caused negative environmental and economic impacts in Thailand. A low-cost, small-scale pyrolysis kiln comprised of a cylindrical tank, gas circulating pipes, a kiln stand, and a manual drum lever was constructed and used to produce biochar from coconut shells in this study. The air intake and holding times for the biochar production process were varied. The biochar yield was 30.67% to 36.22%, or 4.6 kg to 5.4 kg per day per unit. The biochar porosity and fixed carbon content increased as the air intake and holding times were increased. The BET surface areas were 7.54 m²∙g-1 to 63.17 m²∙g-1. The pH values of biochar were alkaline, in the range of 7.34 to 10.24. Therefore, biochar can be used as a soil amendment material. The Net Present Value (NPV), the Internal Rate of Return (IRR), and the payback period are 52,757 THB (1,459.79 USD), 18.71%, 4 years, 10 months, and 27 days, respectively. According to economic analysis, investing in coconut shell biochar production under optimal conditions using the developed kiln is acceptable and can be viewed as a potential approach to providing additional economic benefits for coconut-based enterprises and the Thai community.