Design and simulation of coconut shell charcoal briquette dough mixing machine for small and medium enterprises

Coconut shells are coconut waste that is still not widely utilized. One of the uses of coconut shells that is currently used and continues to be developed is as briquettes. Indonesia has a huge opportunity in the briquette export market, one of which is that briquettes from Indonesia have a high calorie content. One of the stages of making briquettes is the mixing process using a mixer. The use of mixers in large industries uses horizontal shafts that have the advantage of large stirring capacity, but the disadvantage is that the containers used are fixed, and the large size of the mixer makes it expensive, causing it to be less efficient for the UMKM industry to use. Based on this reason, the researcher designed a vertical shaft charcoal briquette mixer with a capacity of 10 kg and simulated the mechanical strength of the stirring shaft material to get a safety factor value. The results of this study obtained three vertical mixer shaft designs, including the design of bread mixers, paddle, and turbine models. Based on the simulation results, the bread mixer shaft got the highest safety factor of 1.6936, then the equivalent von-misses of 121.04 MPa, and total deformation of 0.44424 MPa. On the mixer paddle mixer shaft, the lowest safety factor was 0.5853, then the equivalent von-misses were 350.25 MPa, and the total deformation was 3.3639 MPa. On the mixer shaft of the turbine mixer, the safety factor is 1.2286, then the equivalent von-misses are 166.86 MPa, and the total deformation is 1.0357 MPa. The design results of the selected vertical shaft charcoal briquette mixer will be designed with an electric motor as the main driving force. The shaft on the electric motor is connected by the Oldham coupling to transmit power from the electric motor to the mixer shaft.