Addressing decision making for remanufacturing operations and design-for-remanufacture

Figures & data

Table 1 Definitions of secondary market processes (Ijomah 2002).

Remanufacturing

The process of returning a used product to at least OEM original performance specification from the customers' perspective and giving the resultant product a warranty that is at least equal to that of a newly manufactured equivalent

Reconditioning

The process of returning a used product to a satisfactory working condition that may be inferior to the original specification. Generally, the resultant product has a warranty that is less than that of a newly manufactured equivalent. The warranty applies to all major wearing parts

Repair

Repairing is simply the correction of specified faults in a product. Generally, the quality of a repaired product is inferior to that of the remanufactured and reconditioned alternative. When repaired products have warranties, they are less than those of newly manufactured equivalents. Also, the warranty may not cover the whole product but only the component that has been repaired

Figure 1 A hierarchy of product recovery processes (Ijomah 2002).

Table 2 Past and present aerospace industry business models.

Characteristics	Past business model	New business model
Initial product price	High capital expenditure for the customer	Low capital expenditure for the customer
Quantities of spares	Spares sold to customers	The company does not sell spares to Total Care customers but stores spares for maintaining engines under the total care scheme
Reliability	Same	Same
Customer expectation	Lower	Increased
Competition	Low	High
Source of profit	Spares sale	Service of engine at a pre-agreed rate (£x/hour) over a predetermined period
	High product price
Period when profit is obtained	Point of sale of engine and spares	Income fixed over engine life at predetermined cost per hour flying
Focus on customer needs	Lower	Higher
The company needs and customer needs	The company needs not as closely tied to customer needs	The company needs much more closely tied to customer needs
Incentive to overhaul	Low for customer	Low for The company because it bears the costs of it
	High for RR	Low for customer because it disrupts work

Table 3 Some principal operations control issues highlighted by the case-study work.

Issue	Causes	Reason	Some solutions
Uncertainty	Demand volume variability	• Unforeseen demand fluctuations: this is especially relevant for remanufacturers without contracts as they must take jobs as they become available	• Contracts with customers
		• Demand seasonality, e.g. compressors are more likely to fail in very warm weather as they are forced to work harder then	• Build/partial build for stock
			• Subcontracting agreements for times of unexpectedly high demand
			• Frequently forecast and update resource needs
	Core quality	• Internal components' quality typically cannot be assessed visually as it is not reliant on product's age, make or model	• Keep a bank of casual and temporary labour
			• Monitor suppliers regards quality of their cores
			• Help suppliers improve core handling thus reducing damage in transportation
	Core quantity	• Obtaining adequate used products to fuel remanufacture is a key issue	• Contracts with suppliers
			• Offer cash back for cores
			• Other strategies to boost reverse logistics, e.g. core must be returned to obtain a remanufactured product
	Product type variability	• The remanufacturer typically accepts all orders and all cores offered. Given the high variety of product types, until cores arrive it is impossible to decide whether appropriate parts, and sometimes skills, are available to fulfil particular orders	• Contracts with customers as this reduces variety of product types or at least makes known the types that would normally be received. This is because a contract generally states the product types it covers. However this is not fool proof as even with contracts it is impossible to precisely forecast the quantity and type of cores that will be received. For example it is impossible to predict when customer's products will fail
	Technical knowledge availability	• OEM's are often unwilling to provide them with the product information they need for remanufacturing because they regard remanufacturers as rivals	• Contracts with OEM's thus improving access to their product design information
			• Effectively store product information obtained from experience
	Replacement parts availability	• There may be few suppliers of some old parts and the parts cannot always be sourced from used components, thus it is often uncertain whether required parts can be obtained	• Keep an inventory of spare parts ‘just in case’
			• Start to manufacture some small but rare components of strategic importance
			• Contracts with customers thus specifying the type and level of work that must be carried out on particular components. For example there may be a list of components that must always be discarded whatever their condition. This determines in advance the prognosis for a significant proportion of components. This assists forecasting for component requirement
	No possibility of adjustment	• Tolerances that are too tight	• Keeping inventory of spare parts ‘just in case’
		• Failures damaging parts to the point that their remanufacture would be too costly
Difficulty of knowledge acquisition and processing		• Extreme product variability thus the need to obtain and assimilate vast amounts of information to assist decision making	• Implement a sound data/ information management system to optimise information storage and retrieval
		• Product service history unavailability. The condition of a used product depends on its history and working environment rather than by its age or make. However, customers do not often record their product's service history	• Effective storage of product's failure history from experience to facilitate remanufacture of similar products in the future
		• Product technical information unavailability. Intellectual property rights restrictions as OEM's may be unwilling to provide product design information	• Contracts with OEM's
			• Reverse engineering. In this instance this is where a remanufacturer assesses a correctly functioning product to obtain information with which to remanufacture it on its failure
Flexibility issues		• Environments such as remanufacturing with high variability coupled with high uncertainty are prone to unplanned occurrences and flexibility provides an efficient channel for coping with a unplanned event. However, labour costs are high for highly skilled workers. Also, there is a paucity of effective, certified remanufacturing training schemes	• Subcontracting, multi-skilled employees

Table 4 High level DFRem guidelines.

Process activities	Product/design characteristics			Environmental considerations/safety
	Material	Assembly technique	Product structure
Inspect product	Use materials that will survive the inspection process	Use assembly techniques that allow easy access to inspection points	Structure to facilitate efficient and effective inspection	Use non-hazardous material
	Clearly identify product material	Ensure that assembly methods and joint locations do not conceal product details	Mark inspection points clearly	Use environmentally friendly materials
			Clearly identify product technical details, e.g. make, model and year of manufacture, etc.	Use environmentally friendly assembly techniques
Clean product	Use product materials that will survive the cleaning process	Use assembly technique that will withstand the cleaning process but that will not allow disassembly without damage to components that have potential to be reused	Ensure easy access to all areas to be cleaned	Avoid hazardous or banned cleaning agents
	Use durable materials for identification methods, e.g. avoid use of stickers as these may detach during cleaning		Ensure good resistance to dirt accumulation, e.g. avoid sharp edges and thresholds that may attract dirt	Use environmentally friendly cleaning agents
	Avoid materials that are difficult to clean, e.g. material with pitted surfaces		Ensure ease of handling, e.g. reduce product unit weight where ever possible without limiting functionality or required durability
	Minimise number of different materials used in the product thus limiting use of variety of cleaning agents		Provide handles if product is heavy or bulky
			Ensure marking on product can withstand cleaning
	Use easy-clean material without cleaning residue
Disassemble product	For components destined for reuse ensure that their materials are sufficiently durable to survive disassembly	Use assembly methods that would allow disassembly without damage to components	Arrange components for ease of disassembly	Disassembly process should not require the use of hazardous substances
	Ensure that fasteners' material are similar or compatible to that of base material thus limiting opportunity of damage to parts during disassembly		Reduce the total number of parts	Use an environmentally friendly disassembly method and substances
			Reduce complexity of disassembly, for example by standardising fasteners	Consider design for disassembly techniques that would not prevent reassembly
			Use modular components thus reducing complexity of disassembly because types of assembly techniques are reduced
			Arrange components so that separation joints are easily accessible and easily identifiable
			Minimise the number of joints
			Reduce/eliminate redundant parts
			Simplify and standardise component fits
Sort components	Identify components of similar materials		Reduce/eliminate redundant parts thus limiting sorting time and expense	Use reusable components
	Minimise the number of different materials used for parts thus facilitating component sorting		Use standardised components to limit sorting complexity	Ensure that parts that can not be remanufactured can be reconditioned or repaired or in the worst case scenario can be recycled
	Limit the number of material type per part to reduce sorting complexity		Identify parts by end-of-life destination
	Identify parts requiring similar cleaning or processing modes		Reduce number of parts
			Reduce unit weight
			Provide handles for heavy, bulky, hard to handle parts
			Limit redundant parts
Clean components	Use material that would survive cleaning process	Use assembly methods that allow disassembly at least to the point that internal components can be accessed for cleaning	Ensure that all parts to be cleaned are easily accessed	Do not use banned cleaning chemicals
	Use components that all require or at least can be divided into groups that require similar cleaning agents and procedures. E.g. limit the number of material types per part		Reduce/eliminate redundant parts
	Identify components requiring similar cleaning procedures and agents		Arrange components so that all can be accessed for effective cleaning	Use environmentally sound cleaning agents and procedures
			Ensure product surfaces are smooth and wear resistant
Remanufacture/replace components	Use materials that are at least durable enough to survive the refurbishment process	Use assembly methods that would allow disassembly at least to the point that internal components and sub-systems requiring work can be accessed	Reduce/eliminate redundant parts	Ensure replacements for unremanufacturable components are at least recyclable
	Use materials that do not prevent upgrade and rebuilding of the product	Use assembly methods that do not prevent upgrade of product	Structure to facilitate ease of upgrade of product
			Arrange components so that parts that are prone to damage are easily accessible
			Standardise parts
Test components	Identify component material	Use joining methods that allow disassembly at least to the point that internal components and sub-systems requiring it can be accessed for testing before and after refurbishment	Structure to ensure ease in determining component condition	Use environmentally friendly test procedures and methods
		Input fault tracking device	Component structure should be such that testing is sequential in that it mirrors the order in which the product is reassembled	Limit resource used in test, e.g. energy, electricity, water, etc.
			Minimise the disassembly level required to effectively test components
			Reduce test complexity
			Clearly identify component load limits, tolerances and adjustments
			Standardise tests

Ijomah, W.L., 2002. A model-based definition of the generic remanufacturing business process, Dissertation (PhD). The University of Plymouth, UK

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