How to facilitate improvements in public service systems: propositions for action

Purpose The purpose of this article is to increase the understanding of how improvements can be facilitated in a public service containing multiple actors in terms of identifying, aligning and prerequisites for the improvements. Design/methodology/approach The research utilizes an interactive research approach where data were gathered though a conference, workshop and a survey. The study alternately combines quality management methods such as affinity and interrelationship diagrams with computer aided text mining and latent semantic analysis. Findings The research shows that practitioners must consider interconnectedness between improvements and benefits that are crossing organizational levels of the public service system as well as professional borders. In public service systems, the complex reality can be better understood when improvements and benefits are classified into different organizational layers and an interconnectedness and sequence of improvement areas are acknowledged. Research limitations/implications The research is set in the Swedish public service of the tax-paid sick leave insurance. Future research would benefit by investigating similar cases in other nations and other services. Practical implications The used methodology can be applied by practitioners to enhance a unified understanding of the system required to improve. The study also guides practitioners for how to support, relive hinders and prioritize improvements. Originality/value The research fills a gap of understanding of improvements in public services with multiple actors. As this area is difficult to improve, a novel combination of qualitative and quantitative methods paved the way for deeper and more unified understanding of the system

On assessing grindability of recycled and ore-based crankshaft steel: an approach combining data analysis with material science

Material-related grindability variations when grinding recycled and ore-based steel can significantly impair the process efficiency during finishing of automotive crankshafts. To address this problem and to achieve more robust grinding processes, the underlying causes of variation need to be understood. The present work investigates the feasibility of using quality data obtained during production to study grindability variations and identify material-related effects. Analysis of non-destructive inspection protocols indicates steel supplier-dependent differences in grindability. However, no systematic grindability differences between recycled and ore-based steel could be identified. Possible correlations between grindability and material characteristics obtained from supplied steel certificates are discussed

POD GENERATED BY MONTE CARLO SIMULATION USING A META-MODEL BASED ON THE simSUNDT SOFTWARE

A recent developed numerical procedure for simulation of POD is used to identify the most influential parameters and test the effect of their interaction and variability with different statistical distributions. With a multi-parameter prediction model, based on the NDT simulation software simSUNDT, a qualified ultrasonic procedure of personnel within Swedish nuclear power plants is investigated. The stochastical computations are compared to experimentally based POD and conclusions are drawn for both fatigue and stress corrosion cracks

Case depth evaluation of induction-hardened camshaft by using magnetic Barkhausen noise (MBN) method

Magnetic Barkhausen noise (MBN) method is one of the non-destructive\ua0evaluating (NDE) techniques used in industry to monitor the quality of ferromagnetic products during manufacture. In this article, case depth evaluation of the camshaft lobes by this means after induction hardening is described. A\ua0routine industrial monitoring practice is found to have limitation to evaluate the thickness of this process-hardened\ua0layer. With the aid of metallography on selected samples, this uppermost layer is found to have one, or more than one microconstituents. This infers that each type possesses different physical properties in response to the MBN measurement. Consequently, the interpretation of the MBN signal/data for case depth evaluation is not straight-forward.\ua0From metallography, a\ua0qualified component should have a\ua0uniform layer of martensite with grains ≤ 50\ua0\ub5m and the thickness around\ua03.0–5.0\ua0mm. This gives the magnetoelastic parameter (i.e. mp) in a\ua0range of\ua020–70 in industrial MBN measurement. The mp outside this range corresponds to either a\ua0non-martensitic\ua0type or a\ua0martensitic type with grains > 50\ua0\ub5m. In fact, the characteristic features of a\ua0Barkhausen burst like peak intensity, width and position can be used to categorise different microstructural conditions. Then, the case depth of the qualified components, or the thickness of the qualified martensite, can be estimated. Statistical regression decision tree model helps to divide this qualified group into three sub-groups\ua0between 3.0 and\ua06.0\ua0mm, and each can be identified by the decision criteria based on the specific ranges of the mp reading, the RMS of peak intensity and the peak position. In the end, a\ua0physical model is used to show how the difference of microstructures is influencing the magnetic flux, and thus the mp. Nevertheless, more information is needed to improve the model for this application.

The Right Evaluation Method - an Enabler for Process Improvement

This paper aims at describing the procedure where an alternative evaluation process was developed to support the improvement of both welding and weld quality evaluation. Welded structures are important when striving for reduced fuel consumption due to vehicle weight. Hence good control of the fabrication process is critical to keep welding performance on target, avoiding waste in terms of added weight and overproduction. The resulting distribution of weld weight has shown to be an important control parameter in the sense of keeping cost down. To identify the causes for deviations between actual and theoretical weld weight, information about the weld was needed. The currently used evaluation method showed not to be capable of giving the information needed. It was necessary to know the throat size as well as weld geometry. The current evaluation method introduced more variation due to the measurement than the actual fabrication process itself, leading to drift of process target and overproduction. To fulfil the need of information, that different functions within the company had, a PULL-approach was used. The information need, information presentation and sequence were outlined for each information receiver individually. An alternative measurement method was developed and named WIA – Weld Impression Analysis. The method consists of two parts; creating the replica and analysing the shape in an image analysis program. The method was tested to see if it was capable of delivering accurate and precise measurements, satisfying repeatability and reproducibility requirements for this particular situation. A thorough measurement system analysis was carried out. The measurement system assigned 98.98% of the total variation to part-to-part variation corresponding to long-term process variation. The variation that stems from taking the impressions and preparing them was as well investigated, also showing satisfying results. Finally it was investigated if the impressions reflect the true shape of the welds accurately. The results showed a tendency of slightly higher cross sectional areas in the range of 0-3 %. This however indicated that the accuracy of the measurement system was sufficient for its purpose. The PULL-approach generated a sufficient method which enabled the possibility to perform process improvement and gain large production cost savings

Surface integrity investigations for prediction of fatigue properties after machining of alloy 718

Fatigue performance is crucial for gas turbine components, and it is greatly affected by the manufacturing processes. Ability to predict the expected fatigue life of a component based on surface integrity has been the objective in this work, enabling new processing methods. Alloy 718 samples were prepared by different machining setups, evaluated in fatigue testing and surface integrity investigations. These results generated two predictive statistical multi-variate regression models. The fatigue correlated well with roughness, residual stresses and deformation. The two models showed great potential, which encourages further exploration to fine-tune the procedure for the particular case.The results from this work was granted from the research project G5Demo-2 [2013-04666] and SWE DEMO MOTOR [2015-06047] financed by VINNOVA, Sweden’s innovation agency. Special thanks to GKN Aerospace Sweden AB. The authors also would like to thank the KK- foundation and the SiCoMaP research school

The Influence of Correct Transfer of Weld Information

ABSTRACT This study aims at identifying the causes for deviations between actual and theoretical weld weight. Previous performed studies have shown examples of up to 40% extra weld consumables used in some cases. One consequence is of course higher production cost but it can also give increased weight leading to higher fuel consumption and decreased payload. An interesting aspect is that generous margins on specific production measures dilute important feedback of process variation information preventing and prolonging structural root cause analysis. The causes for the observed deviations can heritage from several areas, both technical and within the information handling. The investigation shows that single components of the information structure and system, such as unsuitable demands as well as incapable evaluation methods, significantly influences the reliability of the entire manufacturing process. The common factor concerning when problems occur, seems to be the ability of correct information transfer between different functions in the organisation preventing the mismatch to appear in the interface. Suggestions for improving this situation include cross functional agreements as well as new measuring methods

A Virtual Design of Experiments Method to Evaluate the Effect of Design and Welding Parameters on Weld Quality in Aerospace Applications

During multidisciplinary design of welded aircraft components, designs are principallyoptimized upon component performance, employing well-established modelling and simulationtechniques. On the contrary, because of the complexity of modelling welding process phenomena,much of the welding experimentation relies on physical testing, which means\ua0 welding producibility aspects are considered after the design has already been established. In\ua0 addition, welding optimization research mainly focuses on welding process parameters, overlooking the potential impact of product design. As a consequence, redesign loops and welding rework increases product cost. To solve these problems, in this article, a novel method that combines the benefits of design of experiments (DOE) techniques with welding simulation is presented. The aim of the virtual design of experiments method is to model and optimize the effect of design and welding parameters interactions early in the design process. The method is explained through a case study, in which weld bead penetration and distortionare quality responses to optimize. First, a small number of physical welds are conducted to develop and tune the welding simulation. From this activity, a new combined heat source model is presented.Thereafter, the DOE technique optimal design is employed to design an experimental matrix that enables the conjointly incorporation of design and welding parameters. Welding simulations are then run and a response function is obtained. With virtual experiments, a large number of design and welding parameter combinations can be tested in a short time. In conclusion, the creation of a meta-model allows for performing welding producibility optimization and robustness analyses during early design phases of aircraft component

Variation in the hierarchy of welding production

Development of strategies for cost effective welding quality assurance is depending on knowledge from and communication between many functions in and supporters to the value chain of production of welded structures. Product development dimensions and estimates likelihood of failure, production monitors and develops process capability and quality/inspection assures measurement system accuracy and precision and estimates probability of detection. Their purpose is of course to avoid catastrophic failures on the field.This investigation reveals that the view and language on risk-based inspection on welds is not the same between industries and not the same across different functions within the same industry. The consequence is that the underlying problem to welding inspection of inner faults seems not to be a technical issue in first-hand, instead development rather is caught on difficulties on how to create overall consensus on how both root causes and risks with quality variation in the tolerance chain should be identified, assessed and mitigated. This displaces the issue from technical to managerial. This investigation supports an elevation of the issue in order to facilitate future interdisciplinary development to bridge horizontal and vertical fragmentation. Three explaining concepts and one hypothesis on root cause are introduced: •Concepts for elevated problem characterization are: between industries differences, within industries range of perspectives, and a hierarchy of system levels related to WHY, WHAT and HOW.•A hypothesis used for problem characterization is the difference between industries where NDT development is driven by the existence of public authority requirements and technical directions or not, which results in different prerequisites (will and need) to technically develop new NDT technology and procedures

Variation in the hierarchy of welding production

Development of strategies for cost effective welding quality assurance is depending on knowledge from and communication between many functions in and supporters to the value chain of production of welded structures. Product development dimensions and estimates likelihood of failure, production monitors and develops process capability and quality/inspection assures measurement system accuracy and precision and estimates probability of detection. Their purpose is of course to avoid catastrophic failures on the field.This investigation reveals that the view and language on risk-based inspection on welds is not the same between industries and not the same across different functions within the same industry. The consequence is that the underlying problem to welding inspection of inner faults seems not to be a technical issue in first-hand, instead development rather is caught on difficulties on how to create overall consensus on how both root causes and risks with quality variation in the tolerance chain should be identified, assessed and mitigated. This displaces the issue from technical to managerial. This investigation supports an elevation of the issue in order to facilitate future interdisciplinary development to bridge horizontal and vertical fragmentation. Three explaining concepts and one hypothesis on root cause are introduced: •Concepts for elevated problem characterization are: between industries differences, within industries range of perspectives, and a hierarchy of system levels related to WHY, WHAT and HOW.•A hypothesis used for problem characterization is the difference between industries where NDT development is driven by the existence of public authority requirements and technical directions or not, which results in different prerequisites (will and need) to technically develop new NDT technology and procedures