Failure product design costs

Crude oil and gas from offshore platforms are evacuated by pipeline or alternatively, in the case of oil, by tanker. Pipeline transport is the most common means of evacuating hydrocarbons, particularly where large volumes are concerned. Although a pipeline may seem a fairly basic piece of equipment, failure to design a line for the appropriate capacity, or to withstand operating conditions over the field life time, can prove very costly in terms of deferred oil production. 

Example - determining the failure costs for product design... 

Finally, the main benefit as far as competitive business performance is concerned is the potential for reduction in failure costs. Studies using CA very early in the development process of a number of projects have indicated that the potential failure costs were all reduced through an analysis. This is shown in Figure 2.47, where this potential failure cost reduction is shown as the difference between pre-CA and post-CA application by the teams analysing the product designs. 

To improve customer satisfaction and business competitiveness, companies need to reduce the levels of non-conformance and attendant failure costs associated with poor product design and development. Attention needs to be focused on the quality and reliability of the design as early as possible in the product development process. This can be achieved by understanding the potential for variability in design parameters and the likely failure consequences in order to reduce the overall risk. The effective use of tools and techniques for designing for quality and reliability can provide this necessary understanding to reduce failure costs. 

Chapter 1 of this book starts with a detailed statement of the problem, as outlined above, focusing on the opportunities that exist in product design in order to reduce failure costs. This is followed by a review of the costs of quality in manufacturing... 

The next step is to set performance and cost criteria for the system in order to be able to determine whether the new greener design is acceptable. Chelants are often one of the hidden components in a formulation whose value is only found when the system fails. So, what is the cost of batch failure, product spoilage, laundry not being cleaned, reworking in a pulp mill, and so on Also, what is the target cost per dose for the chelant and related chemicals It is important to set acceptable limits on performance - for example, the formulated product needs to be stable for 6 months or show bleach stability >80% over the 30 min wash cycle. 

Adhesion, whether the bonding of polymers or the adhesion of coatings to polymer surfaces, is a recurring and difficult problem for all industries that use these materials as key components in their products. Designers must often select specially formulated and expensive polymeric materials to ensure satisfactory adhesion (albeit even these materials often require surface preparation). In some cases, entire design concepts must be abandoned due to the prohibitive cost of the required polymer or the failure of crucial bonds. 

Product design starts by one visualizing a certain material, makes approximate calculations to see if the contemplated idea is practical to meet requirements that includes cost, and, if the answer is favorable, proceeds to collect detailed data on a range of materials that may be considered for the new product. The application of appropriate data to product design can mean the difference between the success and failure of manufactured products made from any material. The available plastic test data requires an understanding and proper interpretation before an attempt can be made to apply them to the product design. Details on designing a product can follow a flow pattern as shown in Table 7.6. 

In this chapter, simple analysis techniques are presented that will assist the designer in developing new products to handle the anticipated loading, while keeping stress and deflection within acceptable limits. These techniques will also be useful in product improvement, cost reduction, and the failure analysis of existing parts. The application of simplified, classic stress and deflection equations to plastic parts are presented here. As the complexity of a part increases or when particularly accurate results are required, more exact traditional methods or computerized finite element analysis (FEA) may be required [1, 2, 7-14, 33, 40-45, 62-76, 93, 270, 278, 390-417]. 

Failure Mode and Effects Analysis. The system design activity usually emphasizes the attainment of performance objectives in a timely and cost-efficient fashion. The failure mode and effects analysis (FMEA) procedure considers the system from a failure point of view to determine how the product might fail. The terms design failure mode and effects analysis (DFMEA) and failure mode effects and criticaUty analysis (EMECA) also are used. This EMEA technique is used to identify and eliminate potential failure modes early in the design cycle, and its success is well documented (3,4). 

Failure costs - Internal failure costs are essentially the cost of failures identified and rectified before the final product gets to the external customer, such as rework, scrap, design changes. External failure costs include product recall, warranty and product liability claims. 

Suppose a particular fault in a product is not detected through internal tests and inevitably results in a failure severity S = 5. If around 80% of failures are found by customer testing and 20% are warranty returns, then the expected cost on average for one fault will be 2.8Pc, from Figure 1.13. If the product has been designed such that Cpi = 1.33, or in other words, approximately 30 parts-per-million (ppm) failures are expected for the characteristic which may be faulty, then for a product costing 100 the probable cost of failure per million products produced would be 8400. 

The case studies that follow have mainly come from live product development projects in industry. Whilst not all case studies require the methodology to predict an absolute capability, a common way of applying CA is by evaluating and comparing a number of design schemes and selecting the one with the most acceptable performance measure, either estimated Cp, assembly risk or failure cost. In some cases, commercial confidence precludes the inclusion of detailed drawings of the components used in the analyses. CA has been used in industry in a number of different ways. Some of these are discussed below ... 

The analysis indicated that the conformance problems associated with the hub design had a cost of failure of more than 30%. This would represent at the annual production quantity required and target selling price, a loss to the business of several million pounds. As a result of the study the business had further detailed discussions with their suppliers and not surprisingly it turned out that the supplier would only be prepared to stand by its original quotation provided the tolerances on the hub, discussed above, were opened up considerably (more than 50%). Subsequently, this result supported the adoption of another more capable design scheme. 

---