1. General introduction
The current success of extruded panels and profiles is causing Vytec Corporations to face several problems. Due to an increased silo demand, the sifter efficiency is reduced, resulting in a substantial amount of acceptable material being rejected. Furthermore, the quality of the siding decreased as environmental conditions affected the stability of the extrusion and the performance of the used material. Finally, overuse causes the lines to become plugged. The main cause for these problems can be found in the unbalanced flow from the silos to the extruders when production throughput increases. To alleviate the above-mentioned issues, it is necessary the balance the flow from the resource silos in all possible production situations. In addition, it is also important to increase Vytech’s production capacity to guarantee an accurate response to the growing market demand. The following report contains the necessary information for balancing the silos for Vytech’s current production as well as a comparison of several options for increasing the production capacity. The report answers the following questions concerning silo demand balancing: How should Vytec Corporations hook up the extruders to balance the material flow from the four silos containing substrate? How could all eight extruders be connected to the two silos containing the needed neutral substrate so that the silo flows are as balanced as possible? How can a balanced flow from the silos be maintained in the longer run? Should the output from extruder line 4 be increased to 1400 pounds per hour? Should an extra extruder with the same capacity of extruder 8 be added? What are other options to increase the company’s capacity and how do they influence the balancing of the silos? To answer these questions, an excel model was developed for which this report analyzes the results. The excel-sheets can be found in appendix with a concise explanation of the model (see also appendix 2). For the entire analysis, we assumed that the substrate flow rates are constant and that they are set at the typical substrate flow rates (see also appendix 3). 2. Profile extruding process
Plastics extrusion is a manufacturing process in which plastics are melted and formed into a continuous profile, such as pipes, window frames, films, etc. The material and required additives, i.e. colorants, UV inhibitors, etc., are fed into the extruder through a hopper and feed throat by means of gravity. The extruder consists of a barrel and a rotating extruder screw that is powered by an electrical motor. In the extruder, the material is gradually melted to a homogenous melt by means of friction and heating elements. The screw forces the resin through the extrusion die, forming it into the desired product shape. This extradite is then calibrated and cooled in the calibration unit, after which the cooling continues at the water tank. The haul-off unit pulls the profile through the production line at a constant speed, determining the speed of the extrusion line. At the end of the production line, the continuous profile is cut to the desired measurements by a guillotine blade. A schematic representation of the extrusion process can be found in appendix 1. Currently, Vytech uses a production setup with five silos that hold the compounds and eight extruders that draw the required compounds from the silos. Each siding consists of two parts: an outer capstock layer and an inner substrate core. Every extruder therefore always requires compounds from two silos: the capstock silo, to which it is permanently connected, and a substrate silo, which it ‘chooses’ depending on the colour of the final product. The substrate usage of each extruder can be found in appendix 3. In order to prevent sifter inefficiencies, silo demand of each silo is restricted to 9500 pounds per hour.
3. Silo-extruder configuration
Silo-extruder configuration at full capacity
In a first stage, it is...
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