Jacek Ziemba

A Review of Current and New Measurement Techniques Used in Hot Die Forging Processes

The work presents the possibilities of applying modern measuring techniques, classic and coordinate measuring techniques in the forging industry (various stages of technological sequence), with the use of various measuring tools, instruments and machines applied in workshop metrology. The work points to different aspects of measuring techniques used mainly for two groups of objects, emphasizing their important role in the context of safety (achieved forgings—products) and the significant measurement problems due to the extreme conditions in industrial hot forging processes. The first group comprises various measurements of forgings (control during and after forging and mechanical treatment). The second group includes measurements of the forging equipment involving a broadly understood quality control (geometrical characteristics, surface quality etc.), often combined with comprehensive control and durability analysis of forging tools. The work analyzes the possibility and validity of applying scanning techniques for direct control of the quality and change of the geometry of the tools in industrial forging processes, without the necessity of their disassembly, and also measurement systems of temperature, forces and displacement in forging processes.

Laboratory and Performance Studies of Anti-wear Coatings Deposited on Nitrided Surfaces of Tools used in an Industrial Hot Die Forging Process

Abstract The paper presents the results of laboratory studies performed on produced anti-wear coatings as well as the results of performance tests conducted on tools with these coatings in industrial conditions, in the process of hot die forging. Three different coatings were selected: AlCrTiSiN, Cr/CrN and AlCrTiN, deposited by means of the vacuum-arc method on test samples as well as forging tools used in the hot forging process of a lid. The first part of the paper discusses the results of the studies performed in laboratory conditions, which included: surface morphology by means of SEM, hardness and Young modulus measurements, determination of the chemical composition by means of the EDS method, adhesion tests by means of the scratch method and tribological tests by means of the ball-on-disk method. The obtained results were correlated and applied in the analysis of the performance tests on forging punches with these coatings at an early stage of their performance (up to 4000 produced forgings), which were tested on 19 tools, of which 3 representatives were selected for each coating. A thorough analysis was performed of the wear phenomena and mechanisms and the manner of wear of hybrid layers as well as their resistance to the particular destructive mechanisms. Based on the performed laboratory and performance studies as well as their analysis, it was possible to select the optimal hybrid layer, which enables an increase in the durability of forging tools used in industrial hot die forging processes. The preliminary results showed that the best results for the whole working surface of the tool were obtained for the Cr/CrN layer, which characterizes in high adhesion as well as a lower Young modulus and hardness. In the case of high pressures and the correlated friction, better results were obtained for the AlCrTiN coating, which, besides its good adhesion properties, also exhibited the highest frictional resistance.

Application of Scanning Techniques in the Analysis of the Wear Forging Tools

The work concerns the possibility of the use of modern non-contact measurement techniques in a die forges. In particular, the possibility of using measuring arms with integrated linear scanners to analyze wear of forging instrumentation. The research was divided into two phases. The first step was to analyze tool wear based on direct scanning of their surfaces, then develop a wear-loss curve of the geometric material. In the second step, a selected area of cyclic retrieved forgings from the forging process was scanned for use of an intermediate scanning method—reverse 3D scanning. On this basis, an analysis of the progressive material growth on the selected surface of forgings was made, which was also a loss of material on the tools. The performed analyses showed a good agreement of the geometrical properties of the surfaces (of the selected forgings representing the proceeding wear of the tool) and the geometrical defect of the working impression of the tool, based on the direct measurements during the production process. The obtained results allow for a fast analysis of the forging tool life with respect to the quality and the quantity forging instrumentation.

Lubrication in hot die forging processes

This article presents selected aspects of lubricant application, as well as lubrication methods and devices in the context of forging tool durability and accessories used in die forging processes at elevated temperatures. The properties and applications of the currently used lubricating and cooling agents in selected industrial forging processes were analyzed. The authors’ original studies on the influence of lubricant application, dose size, time and feed direction as well as other factors affecting tribological conditions are also presented. A review of lubricating and cooling systems and devices is provided, as well as a lubricating device built on the basis of the authors’ knowledge and experience is presented. The developed system, implemented into an industrial process, makes it possible to select and maintain its optimal tribological conditions through the control of the size and frequency of the administered lubricant dose. It may be an alternative to the manual lubricant application method, where human error is a factor, or to fully automated, but expensive, lubrication systems.

Wear Analysis of Die Inserts in the Hot Forging Process of a Forked Type Forging Using Reverse Scanning Techniques

This article presents a wear analysis of die inserts used in the hot forging process of a forked forging (yoke), an element applied in steering systems of passenger vehicles. Studies involved the application of an original reverse scanning method intended for rapid and reliable wear analysis of forging tools (with complicated shape) affording easy assessment without the need to dismount tools from the forging unit. The developed method involves analysis of progressive wear of forging tools based on measurements (scanning) of forgings periodically collected from the process and constitutes a useful tool for measurement and testing. As the authors’ earlier works have demonstrated, the proposed new approach to analysis of tool wear with the application of reverse 3D scanning has proven successful in multiple instances in the case of axially symmetrical objects. The presented results of studies indicate that it is possible to utilize the expanded method to analyze the lifetime of forging tools, including tools with complex geometry. Application of the reverse scanning method allows for continuous and practical monitoring of the condition of forging tools over the course of the forging process and should have a positive impact on improving production output and reducing production costs.