In 1997 we created at Pronar the Wheels Department. Production and sales dynamics of steel wheels is constantly increasing, reaching hundreds of thousands of pieces a year. First of all, the high quality of Pronar wheels means that they are eagerly chosen by both domestic and foreign customers.
The high quality of Pronar wheels has made them applicable, among others in trailers, construction, industrial, forestry and military machinery. We make them in a unique cold processing technology. It is the high quality of production, confirmed by certificates, that made the world’s largest producers of agricultural machinery and tyres interested in Pronar wheels.
The wheels produced in Pronar meet the international requirements of ETRTO, EUWA and ISO. In accordance with the assumptions of the “Quality Policy” – the document adopted by the management of Pronar, the company aims to provide buyers with the highest quality products and services. Pronar achieves a high level of customer satisfaction and satisfaction, among others thanks to the use of the Integrated Management System. Caring for the quality of products begins with a thorough quality control provided by the material suppliers.
By controlling at individual stages of the production process and ending with a random checks of the finished product. A very important factor in the production of wheels is the employees who undergo an appropriate training process. It depends on them what dimensions the products will have. Employees at individual stages of production check their parameters, and the correct setting of machines is supervised by foremen and others.
In case of implementation of new products, the employees of the Technological Department and the Production Department carry out technological tests under the supervision of the Quality Control Department. Wheels are a key element for safe driving, so they require a very complex, multi-stage and rigorously supervised production process. They are characterized by such parameters as: degree of resistance to pressures and resistance to loads resulting from their exploitation. PRONAR wheels are manufactured from a cut of metal sheet, which results in a strip corresponding to their width. The length of the belt, on the other hand, is the circumference of the wheel, which after conversion gives the diameter of the future wheel. A roll is a coiled strip of sheet metal of a certain width, from which, after the profiling process, the initial or final shape of the wheel will be formed. The length and width of the metal sheet strip is a standard value, which has an upper and lower deviation value. Then the metal strip (coil) is rolled up and welded, which gives it the shape of a circle.
The next step is to profile the coil. This is a very important process of creating a circle, during which the coil gets its intended shape. By selecting profiling rollers we determine the final parameters of the coil, such as: internal diameter, flange dimensions, etc. In parallel with the production of bare rims, discs and lugs are produced, which we also subject to the control process, according to the procedures adopted in the department. In the bare rims we measure: circumference by bead, inner bare rim diameter, their width, thickness and height and width.
In discs we measure: external diameter, disc thickness, central hole diameter, pitch circle diameter and bolt hole diameter. Therefore, if the inspected coil is qualified as compliant with the technical drawing and has the required parameters, we send it to the next production stand. When producing the lug wheel, it is important to correctly adjust the offset of the lug to the coil. The future track width of the machine depends on this setting.
A very important stage in the production of disc wheels is pressing the wheel into the bare rim. The stage to be strictly controlled is to determine the position of the disc or lug to the bare rim. Defined as ET (offset), i. e. the offset of the disc against the coil. During the ET determination, the axial runout of the wheel shall be corrected, if necessary. The ET measurement carried out by the quality controller always takes place in the presence of the set-up technician and supervisors. The measurement results are recorded in the measurement cards and in the work cards. After the ET is established, the circle is spot-welded and then sent to the welding rotors. This is where the process of joining the disc or lug to the bare rim takes place.
Nowadays, most of the wheels are welded using automatic welding machines that press the disc into the bare rim. They measure the wheel run-out and connect the elements with the weld joint. The run-out measurement is carried out on a Wheels Department welding machine using advanced testing methods. It is then subject to re-verification at the measuring station of the Quality Control Department. If the first wheel in the batch conforms to the assumed standards and falls within the assumed measurement limits, it shall be released for series production. In the next stage, we check the quality of the wheels in accordance with the valid instructions for product inspection at the Wheels Department. In the automatic cycle, the wheel edge is also machined. After welding, the wheel is placed on a grinding stand where sharp edges and burrs are removed.
Then there is a multi-stage painting process, in which the bath parameters and paint thickness are controlled. Wheels leaving the paint shop are visually reassessed for cracks and other imperfections. Then we pack the products in accordance with the packing instructions and place it in the storage area. From each production batch we take samples in the form of a finished product, which we subject to additional measurements. We carry out all key wheel measurements together with visual evaluation of the surface and create a measurement card together with a quality certificate. Before sending the products back to the warehouse, the inspector is obliged to confirm the compliance of the batch with the assumed requirements and procedures in force at the department. If the quality of the wheels at any stage of production shows non-compliance with the technical documentation, the whole batch is retained.
To sum up, the most important goal of the Wheels Department is to produce products of the highest standards that bring the greatest satisfaction to customers. In order to achieve this, a whole series of procedures for in-operational checks must be followed. We have assigned strict definitions of the activities for each job position for a specific production stage. The production of a wheel with the assumed parameters is preceded by a whole series of control measurements, correct positioning of machines, selection of the best possible welding process and metal processing. This ensures that the product meets the expectations of the buyer and the high quality of Pronar wheels.
The Quality Control Department at the Wheels Department has the necessary technical documentation for each technological process and has the necessary measuring tools. Pronar places great emphasis on the implementation and development of new measurement technologies. More and more often they are electronic devices, easier to use, enabling quick and accurate measurements. All measuring instruments are supervised by the Measuring Chamber, according to the procedure “Supervision of monitoring and measuring equipment”. In addition, we conduct an analysis of the MSA measuring system.
In solving quality problems, we also use various methods and quality tools, such as: MSA, CpK, Pareto Diagram and 8D report. They are mainly aimed at continuous improvement of quality procedures and processes based on the PDCA Deming cycle, which refers to quality management and consists in applying an appropriate approach to the implementation of specific activities and processes.
The employees of the Quality Control Department are also authorized to perform non-destructive testing VT1 and VT2. The scope of visual inspection mainly concerns the determination of surface defects.
When it is necessary to perform complex geometric measurements, requiring advanced measurement methods, we use measuring arms with a 3D laser projection system. The measuring arm is used to measure points in a three-dimensional coordinate system. The measurement of single points gives the possibility to measure geometrical features.
Therefore, in order to prevent the occurrence of potential defects, the Quality Control Department takes corrective and preventive actions to eliminate possible noncompliances. These activities are analysed in detail by a team consisting of constructors, technologists, production masters and Quality Control Department employees. These relate to control plans and the FMEA (analysis of types and effects of possible errors).