## Procedure for determination of the calibration curve of the measurement device using the method of linear regression

Machines. Technologies. Materials., Vol. 13 (2019), Issue 10, pg(s) 425-429

The result of each measurement consists big or small measurement uncertainty. Many sources of uncertainty, especially in industry measurements, are not well studied and require further researchment. Therefore, it is important to have good knowledge about measurement uncertainty in order to minimize as much as possible.
The results of performed analyse and the study of the opportunities for application of the method of linear regression for determination the calibration curve of the measurement device are presented in this paper. The researchment refers to the assessment of the measurement uncertainty type A and B, as well as the combined and extended uncertainty of the measurement result.
By the fulfillment of the assumption for realization of an engineering experiment, with possession of mathematical, technical and practical experience of the operator and the computer supported analytical process, the calibration curve of the measurement device is determined, as well as the extended uncertainty of the measurement result. In this way, a stable measurement process will be achieved, a consistent measurement result, with an increased level of confidence.

## THE IMPACT OF THE CONSTRUCTIVE PARAMETERS OF THE BUMPER OVER THE CONSEQUENCES DERIVING FROM THE PROCESS OF COLLISION

Trans Motauto World, Vol. 3 (2018), Issue 1, pg(s) 11-14

With the analysis and synthesis of the process of crashing, the impact of every factor is estimated in the generation and the development of the accident, and conclusions are drawn regarding the impact of particular elements from the vehicle over the consequences from the accident.

The bumper system is a component of the vehicle intended to reduce the effects of the bumps on the front and the rear of the vehicle, its components and the shell. The cost of the damage and the protection regarding the bumper are the main criteria used to evaluate the efficiency of the impact of the bumper system, especially at low impact velocity.

This paper is representing the results of a deducted analysis and an investigation of the influence of the bumper system alongside its constructive parameters to the extent of the damage in low impact velocity. The investigation is primarily relating to statistical analysis of average damage, overall weighted average damage and variations in the amount of damage.

## OPTIMISING TECHNOLOGY FOR PRODUCTION OF HIGH FREQUENCY WELDED PIPES MADE OF X60 STEEL

In this research work the Welding technology that implements high frequency contact welding process (HFCW), is presented as a method for automatic steel pipes production. The pipes produced by the HFCW are meant to be used for natural gas transportation.
X60M steel coils with thickness of 6.5 mm are used as a raw material. The outer pipe diameter is φ508 and the length is 12000 mm. The preliminary welding procedure is based on the personal experience, technical knowledge and the expert judgment. A special attention has been paid to the most important welding parameters such as: current frequency, voltage and welding speed. After the welding was finished, an additional heat treatment (normalization) of the welded pipes (joints) was performed at the temperature of 900oC.

In order to justify the proposed welding technology a complex analysis is applied. The first analysis was the chemical analysis of base metal. The next was the nondestructive testing consisted of a visual inspection, and ultrasound testing of the pipes. The destructive testing was consisted of tensile testing, bend testing and the hardness measurement. Besides the analysis of the micro and macro structure of the welded joints, a metallographic analysis is performed as well. Moreover a hydrostatic test and a flattening test were performed as an integral part of the entire testing process. The test results confirmed that the pipes produced with the predicted welding parameters completely fulfilled standard requirements. The manufacturing process for the pipes for natural gas transportation is ready to begin.

• ## INVESTIGATION OF ZINC COATED PANELS Nylofor® 2D Super

Zing galvanized panels were ordered and delivered for the fencing of the factory yard. But immediately after receiving the panel from the deliverer, it was concluded that their quality is suspicious. These panels must fulfil strict standards requirement concerning their quality. To confirm this purchaser engaged the team from the Faculty of Technology ad Metallurgy in Skopje to perform investigation and to check if the panels satisfy quality requirement. The performed investigation consists of the following testing’s: chemical composition of base metal (wire), wire diameter and tolerances, tensile test, weld shear strength test, mesh size and tolerances, coating, visual inspection of panels. Performed investigation confirmed that delivered panels didn’t fulfill necessary requirement for this type of fencing.

• ## COMPARATIVE ANALYSIS OF THE ANALYTICAL METHODS FOR ASSESSING THE PRECISION OF THE MEASURING SYSTEM

The results of performed analysis and the study of analytical methods for assessing the precision of the measuring system are presented in this paper. Studies are related to the methods for assessing the precision based on the range calculation and the method of variances analysis (ANOVA).The importance of each factor in variation inducation in the measurement process is estimated by applying both methods in the analysis of the same measured sample. In order to assess the accuracy and efficiency of the applied methods, the obtained results are compared, which is the basis for obtaining specific conclusions.Reliability of the obtained results from the investigations are verified by applying the tools of programming package MINITAB.

• ## DISSIMILAR WELDING AUSTENITIC STAINLESS STEEL S316 WITH FERRITIC STRUCTURAL STEEL GRADE 300NZS

In this research work, procedure for certification process of dissimilar welding between austenitic stainless steel S316 with structural steel grade 300NZS according EN 15614 standard was explained. Shielded metal arc welding process (SMAW) was used. Welding was performed in PA position with EIS 309 Mo electrode. Qualification test has to confirm that the preliminary welding procedure fulfil quality requirement, and welded joint will satisfy the exploitation conditions. The following investigations were conducted to welded test plate; Visual testing (VT) has to show existence of surface defects in the welded joints. Next step was radiographic testing (RT) in order to check eventually appearing of volumetric defects inside the weld. Finally the plate was cut for mechanical testing. All conducted tests fulfilled requirements except one probe of bend test. Because of that qualification procedure was not successful, and it was completely repeated after two weeks. The repeated welding procedure specification (WPS) was qualified.

• ## THE MOST IMPORTANT MACEDONIAN FOUNDRY COMPANIES

In this paper short reviue about the most important Macedonian foundry companies is given. During prepariation of this work autors visited production units of of the foundry companies and discused with their menegament about the most important things concerning their current work and the plans for the future. It was found that six of the companies are the most important for Macedonian industry. All of them are private companies. They are founded before transition period, and their production is mainly intended for the foreign market. It is important to say that they have very ambitious plans for improvement of technological processes and increase of production.