Warranty Period Research Articles

Investigation on Suitability of Aluminium to Copper in a Radiator

During the development of automobile it was a bigger challenge to prevent the engine & engine components from melting & damages because the heat generated & temperature inside the cylinder is more than the melting points of engine components due to combustion of fuel inside the cylinder. Many researchers & scientist started working for making the arrangement to dissipate the heat of considerable amount to avoid such bigger problem otherwise engine will seize. After a lot of research work on different types of materials to conduct the heat efficiently they came to conclusion that copper is the best material having good thermal conductivity of 385 watt/m-K can be used in the form of heat exchanger & finally they designed a radiator called COPPER RADIATOR. It is in continuous use in all types of automobile across the world. Over a period due to various pressure of availability, manufacturability, performance, reliability, cost, handling, weight researchers started working on use of alternate materials in a radiator in place of copper to match the performance same as copper & getting other benefits. Attempts have been tried on different kinds of materials & finally found that can solve our problem & it will meet most of our objectives & requirements. So, finally it has been decided to make Aluminium in place of Copper radiators which will give benefits in performance, reliability, cost, availability, easy in handling & manufacturing. The design & development techniques will be discussed subsequently. The effort of this project is to replace the costly copper radiator used in automobile by radiator for better reliability, cost benefit, weight reduction & desirable performance. The radiator has a number of features that make it very attractive for vehicle applications in general. Superior durability and reliability in conjunction with its excellent specific values for costs, performance and weight warrant a favorable solution for Heavy Duty Trucks, tractors, Car, earth movers & other Automobile segments. This methodology examines the results based on design, lab testing, and field testing in actual condition. It reviews the field experience compared to Copper/Brass radiators, examines design and mounting features. Durability, external and internal corrosion resistance are emphasized as essential characteristics. A special focus is the thermodynamics of radiators. The result obtained has been summarized as below:(a) Radiator is able to transfer the heat of 27.95 KW same as Copper Radiator. This is the 1/3 rd amount of heat generated in the engine to be dissipated. (b) Cost Reduction of Amount Rs 1923/- it is about 49% saving against existing cost of Copper Radiator. (c) Weight Reduction of 5 Kg, it is 52.08% reduction in weight due to use of Radiator.(d) Reliability & Field Performance is as per copper Radiator, there is no field failure within the warranty period in all types of applications.

Degradation analysis of 28 year field exposed mono-c-Si photovoltaic modules of a direct coupled solar water pumping system in western Himalayan region of India

It is important to understand photovoltaic (PV) module degradation for the design of PV systems. In the present study results of degradation in mono-crystalline-silicon PV generator of a solar water pump after 28 years of outdoor exposure at a western Himalayan location in the Indian state of Himachal Pradesh, are presented. The main objective is to study the impact of PV degradation on solar pump performance, reliability and life-expectancy under field conditions. Main defects observed in PV modules are encapsulant discolouration, delamination, oxidation of front grid fingers and anti-reflective coating, glass breakage and bubbles in back sheet. Hot spots are identified using thermal imaging and degradation is quantified by measuring PV parameters under indoor and outdoor conditions. Sun simulator is used to test degraded modules under standard testing conditions. Average power degradation of PV generator is found to increase 1.4% per year which is reasonable considering materials and technology used about three decades ago. The open circuit voltage is found to show an average increase of 2.8% requiring further experimental investigations. The study has relevance in improving the performance and life-expectancy of PV based systems beyond the warranty period of 25 years by replacing most degraded modules. Follow up research areas are also identified.

Risk Management for Asphalt Road Construction and Maintenance under Performance-Based Contracts

Contractors have been the main risk bearers in most road construction and maintenance projects, especially when they are working under higher-risk delivery systems such as Performance Based Contracts (PBC), where the contractors are more likely to be responsible for both the construction and maintenance of the road for a certain warranty period. This research identified and analyzed the risks that the contractor is subject to under PBCs for hot mix asphalt (HMA) road construction and maintenance projects. The study used a mixed methods research design and was divided into three phases. In the first phase, employing a detailed literature review along with industry interviews, twenty-nine risks were identified in the construction and maintenance phases. In the second phase, risk severity rankings were calculated using probability and impact data that was collected from several contractors and a state agency. In the final phase, a correlation analysis was conducted. The results of this analysis will enable contractors to make adjustments and modifications to address the highest and most severe risks.

On Reliability Improvement of Second-hand Products

This paper presents a cost model to determine the optimal reliability improvement level for second-hand products sold with a free repair type of warranty (FRW). The second-hand product of age x is subjected to an upgrade action of a certain level u before it is sold. We look at determining the optimal upgrade level when not performing and when performing periodic preventive maintenance (PM) during the warranty period in order to reduce the risk of early failures. We investigate the effect of periodic PM along with the reliability improvement on the total expected cost incurred by the dealer. The developed model allows determining from the dealers perspective if PM actions carried out during the warranty period are worthwhile. A numerical example is presented to illustrate the consistency of the proposed approach.

An Integrated Production System Model for Multi Supplier Single Buyer with Non-conforming Item and Product Warranty

This paper develops a multi supplier single buyer integrated production system model. Several suppliers transform raw materials into semi-finished goods or components with constant production rates in order to supply a single buyer. The buyer processes components from the suppliers into finished products with a constant production rate. Non-conforming item and product warranty are also considered in this study. There are non-conforming items in the supplier production lot, in which the number of non-conforming items for each lot is probabilistic and the non-conforming items are reprocessed before they are delivered to the buyer. The result is that a buyer does not bear the cost of non-conforming item. Supplier provides component warranty to the buyer while finished product warranty to the customer is provided by the buyer. Component warranty period from the supplier (Wi) is shorter than finished product warranty period from the buyer (W), which is given and fixed. If a finished product is experiencing a failure in the end customer within the warranty period, a minimal repair will be done. If failure occurs after Wi, the supplier does not bear any warranty cost, but the buyer does, which covers the customer transportation cost and the repair cost. If failure occurs before Wi, the supplier should pay the repair cost and the transportation cost to the buyer while buyer only pays the customer transportation cost. A mathematical model is proposed to determine optimal number of delivery lots in order to minimize the integrated total relevant costs of both buyer and supplier. The cost of the supplier covers the setup cost, holding cost, rework cost, and the product warranty cost, while the buyer cost covers order cost, holding cost and product warranty cost. Approaches to solve the model are also being proposed in this paper, altogether with a numerical example.

A Decision Optimization Model for Leased Manufacturing Equipment with Warranty under Forecasting Production/Maintenance Problem

Due to the expensive production equipment, many manufacturers usually lease production equipment with a warranty period during a finite leasing horizon, rather than purchasing them. The lease contract contains the possibility of obtaining an extended warranty for a given additional cost. In this paper, based on the forecasting production/maintenance optimization problem, we develop a mathematical model to study the lease contract with basic and extended warranty based on win-win relationship between the lessee and the lessor. The influence of the production rates in the equipment degradation consequently on the total cost by each side during the finite leasing horizon is stated in order to determine a theoretical condition under which a compromise-pricing zone exists under different possibilities of maintenance policies.

The optimal extended warranty length of durable-goods-based preventive maintenance behaviour

The extended warranty is an important strategy for the manufacturers to expand their market share. In this work, we studied the optimal extended warranty length considering preventive maintenance behaviour, which mainly avoids the producers and consumers’ moral hazard. Based on the profit function maximization, the optimal extended warranty length under different situations can be achieved. We conducted a simulation analysis to see the influence on preventive maintenance behaviour during the warranty period to the optimal extended warranty length.

RESEARCH ON PROBABILITY FOR FAILURES IN VW CARS DURING WARRANTY AND POST-WARRANTY PERIODS / „VW“ MARKĖS AUTOMOBILIŲ GEDIMŲ TIKIMYBĖS GARANTINIU IR POGARANTINIU LAIKOTARPIU TYRIMAS

The present paper examines the distribution of failures in „Volkswagen“ car during warranty and post-warranty periods. A statistical mathematical model has been developed upon collecting distribution data on car failures. Considering mileage rates, probabilities for a failure in the systems, including suspension and transmission, cooling, electrical, etc., have been determined during warranty and expiration periods. The obtained results of the conducted research have been compared. The reached conclusions have been formulated and summarized. Šiame straipsnyje nagrinėjamas „Volkswagen“ markės automobilių gedimų pasiskirstymas garantiniu ir pogarantiniu laikotarpiu. Surinkus gedimų pasiskirstymo duomenis, sudarytas statistinis matematinis modelis. Atsižvelgiant į automobilių ridą, nustatytos variklio, pakabos ir transmisijos, aušinimo, elektros ir kitų sistemų gedimų tikimybės garantiniu laikotarpiu bei jam pasibaigus. Tyrimo metu gauti rezultatai lyginami tarpusavyje. Suformuluotos ir apibendrintos išvados.

Economic Order Quantity, Process Quality Level, Warranty Period, and Production Run Length Settings

In the present paper, a modified optimal profit model with settings of production and process parameters is proposed, where the larger-the-better product characteristic with the one-sided lower specification limit is considered. The product characteristic is assumed to be normally distributed with unknown mean and known standard deviation. The selling price of product is assumed to be linearly proportional to its warranty period. We also assume that the retailer’s order quantity is negatively correlated with the wholesale selling price and is positively correlated with the warranty period. The single sampling rectifying inspection plan is adopted for determining the quality of product lot. The Taguchi’s quadratic quality loss function is addressed for measuring the used cost of customer for product. The optimal manufacturer’s process quality level, production run length, warranty period, and retailer’s order quantity can then be simultaneously determined by maximizing the expected total profit of society including both the manufacturer and the retailer. Numerical results show that the longer warranty period and the higher product quality level will lead to the larger expected total profit of society.

Abstract 9439: Incidence of New Coronary Calcification: What is the Warranty Period of CAC = 0 in the Multi-Ethnic Study of Atherosclerosis?

Background: While CAC=0 is associated with excellent prognosis, progression to CAC>0 has been shown to confer increased risk. The time interval at which a repeat CAC scan would be reasonable - the “warranty period” of CAC=0 - is currently poorly defined. Methods: We studied 3116 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with baseline CAC=0 and at least 1 follow-up CAC scan per MESA protocol (up to 10 years after baseline). Cumulative incidence of incident CAC was calculated yearly. Cumulative survival fee of CAC was calculated using Kaplan-Meier statistics and additionally modeled using a parametric survival model with Weibull distribution. The warranty period of CAC=0 was defined distribution as the time needed for 15%, 20%, or 25% (number needed to scan [NNS] 6, 5, or 4) to progress to detectable CAC. Results: The mean age of the subjects was 58 ± 9 years with 63% women and mean FRS of 8 ± 6%. Cumulative prevalence of CAC>0 increased with time, from 11% at 2 years to nearly 50% at 10 years. The cumulative incidence rate of CAC>0 was non-linear, increasing from approximately 2.5 per 100 person-years at 2 years to 5-6 per 100 person-years from years 4 to 10. The table shows the estimated warranty period of CAC=0 by gender and baseline FRS CHD risk. Among men, using an acceptable detection rate of 25% (NNS=4 to detect CAC>0), the estimated warranty period of a low, intermediate, and high risk man was 6, 5, and 3 years. For women, the equivalent warranty period was 7, 5, and 4 years. In general, rescanning at 5 years will enable selection of 50% of the individuals with baseline CAC=0 who will go on to have CHD events following their repeat scan over 10-year follow-up. Conclusions: Although limited by lack of yearly CAC scanning, modeling in MESA allows estimation of the warranty period of CAC=0. A general rule would be to rescan low risk CAC=0 patients at 6-7 years and intermediate risk at 4-5 years, although exact warranty periods vary by gender and desired yield of repeat testing.

Abstract 12044: Absence of Coronary Artery Disease by Coronary Computed Tomographic Angiography and the Warranty Period Associated With All-Cause Mortality: Findings From the CONFIRM Long-Term Follow-Up Registry

Introduction: Coronary computed tomographic angiography (CCTA) is widely utilized for the detection of coronary artery disease (CAD). Foremost, the very low risk associated with normal CCTA is an important component for the purpose of cardiovascular risk stratification. To date, however, data that accounts for long-term prognosis of normal CCTA is sparse. Purpose: Using data from a multi-center, global observational CCTA registry, we sought to determine the potential warranty period of normal CCTA. Methods: Among 12,086 patients who underwent CCTA, 7,651 patients without history of previous CAD, aged between 30-74 years, were included in the current analysis and followed consecutively over 5 years. Normal CCTA was defined as the absence of any plaque in the coronary arteries. Annual mortality was calculated and compared with overall patients. The primary event in this study was all-cause mortality (ACM). Results: During a median follow-up of 5.8 years (IQR, 5.3-6.3 years), 120 of all-cause deaths occurred among 3,051 patients with normal CAD. Mean age of the study population was 52±11 years, and 45% were men. Annual mortality rate was 0.68% (95% confidence interval (CI), 0.57~0.82), while annual mortality of overall patients was 1.31% (95% CI, 1.20~1.42) ( p <0.001). When we defined warranty period as a follow-up duration until the estimated mortality reached the threshold of 5% using a Kaplan Meier curve, the warranty period of normal CCTA for ACM was 7.2 years. In subgroup analysis, according to a baseline risk factor profile using Framingham risk scores (FRS), annual mortality rate was 1.31% (95% CI, 0.85~2.03) among patients with high FRS and 0.62% (95% CI, 0.51~0.76) among those with low to intermediate FRS. Conclusion: Absence of CAD by CCTA demonstrates a favorable survival rate with a minimum warranty period of at least 7 years. Persons presenting with a high cardiovascular risk profile displayed a relatively higher mortality, which is similar to overall population. Therefore, they should be considered a distinct group of individuals at-risk by physicians and researchers alike.

Cost optimization model following extended renewing two-phase warranty

In this paper, we study an extended warranty model under which the customer is offered an additional warranty period after the original two-phase warranty expires. Under the original two-phase warranty, the warranty period is divided into two non-overlapping subintervals, one of which is for replacement warranty, and the other is for minimal repair warranty. If the system failure occurs during the original warranty period, the failed system is either replaced or minimally repaired by the manufacturer, and if the failure occurs during the extended warranty period, only the minimal repair is conducted. For the system failure during the replacement warranty period, the failed system is replaced by a new one, and the warranty term is renewed anew. Following the expiration of extended warranty, the customer is solely responsible for maintaining the system for a fixed length of time period and replaces the system at the end of such a maintenance period. During the maintenance period, only the minimal repair is given for each system failure. Such a maintenance model can be considered as a generalization of several existing maintenance models which can be obtained as special cases. The main purpose of this article is to determine, from the customer’s perspective, the optimal length of maintenance period after the extended warranty expires. As the criterion to determine the optimal replacement strategy, we adopt the expected cost rate per unit time during the life cycle of the system. Given the cost structures incurred during the life cycle of the system, we formulate the expected cost and the expected length of life cycle to obtain the expected cost rate. The uniqueness of optimal solution for the decision variable is verified when the life distribution of the system shows an increasing failure rate. Numerical examples are provided to illustrate the proposed optimal replacement strategy.

Optimal warranty policies considering repair service and replacement service under the manufacturer’s perspective

In this paper, under the manufacturer’s point of view, a warranty cost model is proposed in consideration of both repair service and replacement service simultaneously upon the system failure to find the optimized warranty period in terms of an expected cost rate during the warranty cycle. If a failed system can’t be repaired by the threshold warranty servicing time in the warranty service center, the replacement service is provided for the failed system instead of continuing to provide the repair service. Under such circumstance, new warranty cost models are developed and the renewable warranty policy is investigated for free and pro-rata two-dimensional warranty dependent on both failure time and warranty servicing time. From the manufacturer’s point of view, the warranty period is newly defined starting from the system’s purchasing time and ending at the expiration time of the warranty. This paper determines the optimal warranty period by applying Nelder–Mead downhill simplex method to minimize the expected cost rate during the warranty period. The real application is discussed adopting the proposed approach based on the actual field data and numerical examples are presented to exemplify the applicability of the methodologies derived in this paper.

Price and warranty period decisions for complementary products with horizontal firms' cooperation/noncooperation strategies

The purpose of this paper is to explore the optimal strategies on price and warranty period of two complementary products in a supply chain with two manufacturers and one common retailer from a two-stage game theoretic perspective. Five decentralized models are established by considering the two manufacturers' cooperation/noncooperation strategies and the firms' different bargain powers. The corresponding closed-form expressions for equilibrium decisions are obtained. Through a systematic analysis and comparison, some interesting and valuable managerial insights are established. We find that, the retailer always has the advantage to get the higher profit when she is a leader; however, this is not always valid for two manufacturers, for example, two manufacturers' profits when they are leaders and they adopt the noncooperation strategy in the supply chain are lower than that when two manufacturers and the retailer have the identical market power. All channel members as well as consumers benefit from lower retail prices, longer warranty periods and larger profits when the two manufacturers' adopt cooperation action.

Product failure pattern analysis from warranty data using association rule and Weibull regression analysis: A case study

The warranty data plays a crucial role in the improvement of the manufactured product. Association rule analysis is an efficient methodology for eliciting useful information from warranty data by defining the relationships between production data and failure data within warranty period. We extract association rules from warranty data of heavy duty diesel engine in order to find significant patterns of failures along with manufacturing information. We also used Weibull regression to identify influential factors that affect the variation in mean time between failures which are identified from extracted association rules. The results from the empirical study for manufacturing firm “D” provide information as to the areas in which improvements should be made. Moreover, the result for specific failure is able to suggest a solution to overcome short-sighted improvement representatively. This study expects to contribute quality improvement to manufacturing industry which is under coarse warranty data with enormous unrevealed information to draw meaningful information with ease.

Contracting in Medical Equipment Maintenance Services: An Empirical Investigation

Equipment manufacturers offer different types of maintenance service plans (MSPs) that delineate payment structures between equipment operators and maintenance service providers. These MSPs allocate risks differently and thus induce different kinds of incentives. A fundamental question, therefore, is how such structures impact service performance and the service chain value. We answer empirically this question. Our study is based on a unique panel data covering the sales and service records of over 700 diagnostic medical body scanners. By exploiting the presence of a standard warranty period, we overcome the key challenge of isolating the incentive effects of MSPs on service performance from the confounding effects of adverse selection. We found that moving an operator from a basic pay-per-service plan to a fixed-fee full-protection plan leads to both a reduction in reliability and an increase in service costs. We further show that the increase in cost is driven by both the operator and the service provider. Our results point to the presence of losses in service chain value in the maintenance of medical equipment, and provide the first evidence that a basic pay-per-service plan, where the risk of equipment failure is borne by the operator, can actually improve performance and costs.

Market Segmentation Strategies Used by Chloride Exide Kenya Limited as a Competitive Advantage Tool

Market segmentation used as a strategy by firms can enhance their profitability and increase their competitiveness. Chloride Exide Kenya Limited has used it to target particular sections of the market and introduce specific products. A firm’s relative position within its industry determines whether a firm’s profitability is above or below the industry average. The fundamental basis of above average profitability in the long run is sustainable competitive advantage. Competitive advantage is a position that a firm occupies in its competitive landscape. A competitive advantage, sustainable or not, exists when a company makes economic sense that is, their earnings exceed their costs (including cost of capital). That means that normal competitive pressures are not able to drive down the firm’s earnings to the point where they cover all costs and just provide minimum sufficient additional return to keep capital invested. Most forms of competitive advantage cannot be sustained for any length of time because the promise of economic rents drives competitors to duplicate the competitive advantage held by any one firm (Porter, 1980).Market segmentation was found to influence the demand for products and services: in that different market segments had tailor-made products and services. The company’s segmentation strategy considered the customer’s needs, the purpose for their use for example power back-up systems ranging from the powering of lights to powering the computers and other electrical appliances. The findings indicate that the company offers a variety of products and services that might not be required by all customers thus they identity each markets’ needs; groups/segment these needs into a ‘market’ and position their products and services. The company’s segmentation is also helped by its wide branch network which covers a wide part of the country. The company covers corporate clients, hotels and hospitals that power backup systems for uninterruptible operations of their firms. It uses cluster system to analyze their customer base, target direct-mail campaigns and select branch locations through which it positions its product to the targeted segments. Apart from religion, it was established that personality, personal values and psychographic/lifestyle determined market segmentation.The study established that market segmentation leads to provision of lower prices, greater benefits and services that justifies the higher price. Lower prices offered by the company attract more clients thereby increasing clientele base. Provision of additional benefits such as longer warranty periods and presentations on how their products are supposed to work, targeting high income earners. This has helped give the company a competitive advantage. The study also established that market segmentation ensured customer retention as varied customer needs are catered for; lower prices for retail banking, shorter queues and personalized attention. The study indicated that the implementation of segmentation strategy is long term in nature. Further as the environment responds to the implementation of strategy is necessary and thus formulation is under constant review to accommodate effects of the interaction between the organization and environment.

Price and Warranty Period Decision in Different Channel Structures for Durable Product

A decision problem is investigated in a decentralized two-echelon supply chain with one manufacturer and one retailer during a fixed sales time. There are three possible power balance scenarios: Manufacturer-Stackelberg, retailer-Stackelberg, vertical Nash classified by the different influence on the market between the manufacturer and the retailer. Aiming at profit maximization,from the perspectives of the consumer, the manufacturer and the retailer, respectively, the results of the three scenarios are analyzed, in which the retailer price P, warranty period W and the whole price CP are decision variables. Moreover, the sales over time can be characterized by a stochastic Bass model in the form of a non-homogeneous Poisson process (NHPP-Bass model) and the production system is a make-to-order type of system. Finally, A numerical example is provided to illustrate the effects of some key parameters, including the product reliability, price elasticity, and warranty period elasticity, on the optimal settings of the retail price and warranty period.

Threshold Values of Performance Indicators for Asphalt Concrete Pavement to Apply to Pavement Performance Warranty

Abstract The performance warranty system is quite innovative in requiring a contractor’s warranty for pavement performance over a certain period of time. European countries adopted performance warranty systems about 40 years ago. The United States adopted this system in the early 1990s to improve construction quality and performance, as well as to reduce life cycle cost. In Korea, for the purpose of resolving construction management and quality control problems and poor construction, the performance warranty system is considered as part of the solution. The appropriate performance indicators, reasonable threshold values, and warranty periods have to be selected in order to adopt a performance warranty system that requires keeping the pavement performance above a certain level of satisfaction for the warranty period. For this reason, structural, functional, and safety performance were defined first, and then rut depth, roughness, and crack ratio were selected as performance warranty indicators. For the purpose of suggesting performance warranty threshold values that reflect domestic circumstances, pavement management system data were surveyed, a special project was conducted, and a total of 888 sample sections were analyzed. A threshold level at 95 % of each indicator’s distress was determined for the threshold value; this prevents the worst 5 % of poor performance cases. A 14-mm rut depth, 3.6 m/km International Roughness Index, and 20 % crack ratio for five years were selected as threshold values. To avoid early deterioration of pavement, three- to five-year warranty periods are suggested.

Extended Warranty Models: A Literature Review

With the increasing of extended warranty period for complex systems, the extended warranty has aroused more and more attention for manufacturers and consumers. Although the academic research on extended warranty has made some progresses, there isn’t a detailed literature review. Considering this situation, this paper first provides a classification for extended warranty, and develops a taxonomy scheme, then reviews the literatures about the extended warranty model from different perspectives. At last, the brief discussion of future research about extended warranty is put forward in this paper.