Optimisation of Mechanical Machining of an Aluminium Alloy Product

At the beginning of the diploma thesis, he presented the company MLM from Maribor, its production departments, production and products for their end customers. The company has also obtained certificates for quality and reliability, environmental management and energy management system. In the continuation, he presented the manufacture of the product on the first EMAG machine and its machining tools, which were significantly more numerous than on the next machine, as well as the clamping system and calculation of productivity, which is shown in the table and graph.

Problem

At the beginning of the diploma thesis, he presented the company MLM from Maribor, its production departments, production and products for their end customers. The company has also obtained certificates for quality and reliability, environmental management and energy management system. He then presented CNC machines more broadly, their purpose of use, where they are used and what advantages CNC machines have over NC machines, their development and the most important types of components that the machine needs to operate with high precision and fast working and feed movements. ** I state what types of tools we know and use in the company MLM** and which are the best materials for aluminium alloys and the machining tools we need for work – for drilling, cutting. ** Clamping devices are also described, their advantages and disadvantages, and which are most useful for this product,** which is described in the diploma thesis.

Descriptions of industrial robots follow, showing their usefulness and classification, as well as modern processes, their automation and productivity in the industrial process.

Solution and Method

In the continuation, he presented the manufacture of the product on the first EMAG machine and its machining tools, which were significantly more numerous than on the next machine, as well as the clamping system and calculation of productivity, which is shown in the table and graph. In the continuation follows the presentation of the optimisation of the clamping system, which was made specifically for this product, the change of the CNC machine from a turning machine to a milling machine and the robotic cell, where individual segments are described – the magazine, grippers, industrial robot and their operation.

This is followed by a presentation of productivity before and after optimisation, also illustrated with a graphical comparison and a table. The product was presented with a 3D model, where its machined surfaces and the machining tools with which it was machined are also illustrated. The machining tools are also shown graphically, on which surfaces the product is machined. The contained dimensions for the product are given and their tolerances are also described, the machining time on the lathe and machining on the milling machine are stated. Measurement tolerances for the tool are also given.

All calculations are given for both machines and their productivity indices. Hypotheses of the diploma thesis: ** H1: With the robotic cell, the process will be optimised, productivity will increase, costs will decrease.** Hypothesis one is confirmed, as the number of products per hour has increased and the number of machine operators has decreased, which is also presented graphically in the diploma thesis. ** H2: The robotic cell will also be able to be implemented on other machines in the mechanical machining production process.** The second hypothesis is confirmed, as activities are already underway to optimise other production products with the robotic cell. ** H3: With increased automation, the influence of the human factor on product quality is reduced.** Hypothesis three is partially confirmed, because the robotic cell operates smoothly and with equal quality for each product.

Damage to the product has been reduced because the robotic arm always operates at the same speed and force, and grips the product with high precision. However, human influence is still present when setting up the robot's operation.

Results

The goal set in the diploma thesis – increasing productivity, optimising the product and adding a robotic cell – was certainly achieved, as the change of machine – from the EMAG CNC lathe to the MILL CNC milling machine – proved to be very productive. With the new robotic cell, the productivity of machined pieces increased by fifteen products per hour, the number of required workers decreased – ** from two to one, efficiency increased in one year by 1,156 working hours** for machining the same number of pieces.

Given the number of standard hours and the actual time spent, productivity also increased by four per cent, which means that there is less scrap and fewer stoppages in the machining of the product. It should be noted that the machine can work 8 working hours, whilst for the worker one must also take into account a 30-minute break for a snack. All together this means great savings in costs and relief for workers, as the robot can operate continuously, and it also operates reliably and with quality. The machine occupancy is very high, namely 97 per cent, so the main goal remains to increase productivity and maintain the achieved quality and precision of product manufacture.

By reducing machine occupancy, we can also install a new product or further increase the quantities of machined products at the customer's request. With this, the company can satisfy the wishes of its customer or acquire new ones, and is thus also more competitive on the market. Savings in working hours and less scrap should not be neglected either, the quality of products is also higher, whilst workers who operate the machine are also relieved in their work.