The TAPPI T 809 standard specifies a method for the determination of the flat compressive strength (CMT test) of corrugated core paper. This method is performed by making corrugated core paper into laboratory corrugated strips and then testing it in a compression tester to evaluate its anti-crushing performance. CMT testing can predict the potential flat compressive strength of corrugated fibreboards and is an important indicator to measure the mass of corrugated core paper. The flat compressive strength of corrugated core paper directly affects the compressive capacity and service performance of corrugated fibreboards. Therefore, this standard is widely used in the paper and Encasement industries to optimize production processes, control product mass, and evaluate raw material performance.