Repair of Cocoa Roaster Drum

Design specifications

Final client :
Object :
Capacity :

Cocoa roasting factory
Cocoa Roaster Drum
4000 kg

Problem definition

The Cocoa Roasting drum consists of several longitudinal vanes to scoop the bulk material. In order to enlarge the capacity additional plates had been welded, but the drum shell repeatedly cracked and had to be repaired very often.

Contribution of Stemar Engineering

Stemar Engineering analysed the failure mode and compared this with all applicable variable loadings on the drum. The conclusion was that the vanes needed enough room for thermal expansion, but that had been limited by the modification. With the use a finite element it was shown that the situation would much improve if the new vanes were simply cut in shorter parts.


The client saw the proposal as weakening of the design and had to be convinced of this solution with FEA supported argumentation. Finally the client had the drum modified and the cracking of the drum has now decreased to acceptable levels.

Sustaining Results Through Engineering