Effect of compression modes on strength and abrasion of tablets

Abstract

The aim of the research is to determine the impact of the number of compression cycles and turret rotation frequency on the strength and friability of tablets. The decrease in tablet quality is attributed to product sticking to the press tool surface, increased surface roughness, friction coefficient, and adhesive strength. Consequently, the tablet's outer layer exhibits lower strength properties and is prone to rapid deterioration. The reduced strength at higher rotor rotation frequencies is explained by decreased dwell time in the

die and higher ejection speed, which lowers the strength of its outer layers. Increased tablet wear affects subsequent manufacturing operations: dust accumulates in tablet feed channels for blister packaging, hindering their movement, and tablets lose mass during coating application in turret-type machines, among others. Decreased tablet strength leads to its fragmentation during various technological operations and storage. As the rotor rotation frequency increased from 30 to 80 rpm, tablet strength decreased by up to 10%. The most significant reduction in strength was observed at rotor rotation frequencies of 60–80 rpm. Wear resistance in this range increased intensively from 0.2% to 1.2%, exceeding both pharmacopoeial (1%) and recommended (0.5%) standards. After 300,000 compression cycles, tablets lost up to 8% of their strength. This is because at high force of pushing out, the outer layer

of the tablet is destroyed by the high friction forces of the tablet on the die surface. The outer layer of the tablet is then excessively abraded in the subsequent processing and finishing operations.

This type of defect negatively affects the coating process in drum and fluidized bed machines, transportation between equipment, and during blister packaging. For the tablets used in the study on the Korsch XL 400 tablet press, the optimal rotor rotation frequency was determined to be 50 rpm. Increasing the rotation frequency, and thus productivity, is achievable through more frequent polishing of die and punch surfaces.