Sales during the year 1978-1981 approximately 30,000 baht per month. In 1982, CH. Karnchang shop was moved to Si Phraya Road and the business expanded and had sales of approximately 120,000 baht per month.

Around 1984, CH. Karnchang shop had entered the industrial market by joining with Formula Industry Co., Ltd. offered an ISUZU Z 2200 car air conditioning installation kit to Tri Petch Isuzu Sales Co., Ltd. At that time, the products of CH. Karnchang shop also used welded steel raw materials. After that, it was successful in proposing a project to produce Pulley Crankshaft and Pulley Water Pump to Sukosol Mazda Automobile Industry Co., Ltd.

In 1999, CH. Karnchang shop was merged with Sangrompo Autopart Co., Ltd. and the company's business results have grown. The company has brought in various technologies to be able to prepare the production process more quickly, correctly and precisely. For the production line, the company uses computer numerical control machines (CNC) along with high-precision three-dimensional coordinate measuring machines (CMM).

Later, in 2014, Mr. Vichai had a vision for expanding the business. In terms of being both a producer of raw materials and product sellers to increase the chances of competing and reduce production costs. Mr. Vichai has built a new factory located in Thanyaburi district, Pathum Thani province named “Sangrompo Autopart (Thailand) Company Limited''

During the same year, the company raised the quality of production to enter the international level. The company has passed qualified and received ISO/TS 16949 : 2009 and ISO 9001 : 2008 quality system certification from URS Company.

In 2017, the company received ISO/IATF 16949 : 2016 and ISO 9001 : 2015 quality system certification from URS Company as well.