Acquiring Orders using Requirement Specifications for Engineer-to-Order Production

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1 Original Paper J Jpn Ind Manage Assoc 64, , 2014 Acquiring Orders using Requirement Specifications for Engineer-to-Order Production Jiahua WENG 1, Shingo AKASAKA 2 and Hisashi ONARI 1 Abstract: Engineer-to-order production is an approach in which a firm designs and produces a product that matches the requests of its customers. Usually, at the inquiry stage, the product specification items provided by the design/engineering department are used for discussions between the sales staff and the customer. However, since the customers are not familiar with all the product specifications, commonly, the product specifications are proposed by the sales staff according to his/her experience. Therefore, sometimes a relatively complex product specification (implying high price) may be proposed because of which the customer may not be satisfied; then, extensive discussions are conducted among the customer and the sales, engineering, and even production departments of the firm. This inefficient process may lead to order loss. In contrast, even when the customer is satisfied, the specifications (price) may be underestimated when the product specification is designed in detail after the contract is signed, and may lead to financial loss for the particular order. Therefore, the ability to accurately grasp customer requirements at an early stage is an essential factor. To solve this problem, this paper focuses on the description of the customer requirements. Instead of product specifications, customer requirement specifications are proposed to be used at the inquiry stage. This study uses mixers and drilling machines as case studies. Detailed customer requirement specifications are designed for these two kinds of products. The results show that the proposed description models are practically useful and can be translated into accurate product specifications. Key words: Engineer-to-order (ETO), Customer requirement, Product specification 1 INTRODUCTION This study focuses on the engineer-to-order (ETO) manufacturing firms that are required to design an entire product that matches the requests of its customers. Typical products include machine tools such as machining centers and drilling machines. Since these kinds of products are used for production, their specifications are largely influenced by the machine s expected output product. For instance, an ETO firm s customers can be manufacturing firms that produce key components of electronic devices, or various other final products. Since both the ETO firm and its customers are manufacturers, hereafter in this paper, the ETO firm will be specifically referred to as the equipment manufacturer. Equipment investment is undertaken when a new 1 Waseda University 2 Hitachi, Ltd., Received: November 30, 2012 Accepted: October 31, 2013 product is introduced in the market, a new factory is set up, production is increased or old/broken machines need to be replaced. This paper especially focuses on the first two situations which entirely new equipment is required. At the inquiry stage, the equipment (product) specification items provided by the design/engineering department are used for discussions between the sales staff and the customer. However, since the customers are not familiar with all the product specifications, commonly, the specifications are proposed by the sales staff according to his/her experience. Therefore, a relatively complex product specification (implying a high price) may sometimes be proposed because of which the customer may not be satisfied; then, extensive discussions are conducted among the customer and the sales, engineering and even production departments of the firm. Determining the final specifications of the equipment usually takes a long period of time (e.g. several months). This 620 J Jpn Ind Manage Assoc

2 inefficient process may lead to order loss. Moreover, because of the intense competition in this industry, ETO firms tend to form contracts with their customers before the product specifications are fixed; otherwise, they may lose the opportunity to acquire an order. However, acquiring an order may lead to financial loss because the product s final specifications remain undetermined; hence, ETO firms can only roughly estimate the price by referring to similar products that they have produced in the past. Therefore, understanding a customer s requirements becomes a key factor for quickly and accurately determining a product s specifications. Reviewing the literature related to the customer requirements, we find that it can be categorized into two types: one that is based on customer requirement analysis and another that is based on automatic generation of customized product configurations. In the literature on the former type, such as Refs. [1],[2], quality function development and Kano s model are well discussed. For the latter type, such as Refs. [3]- [7], product family architecture development and constraint satisfaction problem-solving are mainly discussed. Most of the literature treats customer requirements as functional requirements, such as car speed and car capacity [3]. Further, some of the literature expresses customer requirements as direct requests for components of the product, such as memory of 512 MB and an LCD of 14.1 inches [4]. However, functional requirements are still viewpoints from the product side. Our target products are equipment such as machine tools. It is not possible to acquire all functional requirements for a product from the customer. For example, one functional requirement of a mixer can be the agitation speed. However, the customer may have no knowledge of this parameter. All he/she is concerned with is the type of materials that he/she wants to mix. Further, it is difficult for a customer to understand the components of certain equipment. For example, one component of the mixer is a motor, which is not easy for the customer to choose. Therefore, our aim is to design a customer requirement description model by which the sales department can efficiently acquire orders. The description is from the viewpoint of the customers rather than that of the product. After the basic concept of customer requirement description (hereafter, we call it the requirement specification) is proposed, two case studies are conducted to confirm the practical use of the proposal. Furthermore, the relationship between customer requirement specifications and product specifications (hereafter, we call it the product physical specification) are discussed. The rest of this paper is organized as follows: first, the description model for customer requirements is described in section 2. Detailed designs for mixers and drilling machines are described in sections 3 and 4, respectively. Translations from customer requirement specifications to product physical specifications are also mentioned. Finally, conclusions are drawn and future directions are discussed in section 5. 2 CUSTOMER REQUIREMENT DESCRIPTION MODEL 2.1 Concept of Customer Requirement Description Model The customer requirement description model includes customer requirement specifications, product physical specifications and the translations of customer requirement specifications into product physical specifications (the highlighted part of Fig. 1). Since there are a large number of research studies on product configuration for reference, this study will only discuss the customer requirement description model. Customer requirement specification Product physical specification Customer requirement acquisition Parts/ Components specifications Product configuration Fig. 1 Relationship among the three types of specifications 2.2 Definition of Customer Requirement Specification Since the target products are production equipment, the customer (user of the equipment) should know the expected output product and the Vol.64 No.4E (2014) 621

3 expected production efficiency. Therefore, the customer requirement specifications are designed to clarify the production needs of the customized equipment. Four types of machine tools drilling machines, machining centers, wire electrical discharge machines and cold rolling mills are investigated to understand the common customer requirements. For these types of machines, we managed to obtain 71 different customer requests. Some examples of these requests are as follows: To be able to roll 1-mm-thick aluminum To be able to cut a multifaceted workpiece To automatically exchange the tool when the current tool breaks Height of the machine to not exceed 2,400 mm To be able to process 60 wafers/h These requirements are grouped by the viewpoints of 5W1H (Table 1). Table 1 Requirement items grouped by 5W1H 5W1H Definition Requirement Description When When does the Due date customer need the equipment? Where Where will the equipment be set Production environment (e.g. power voltage etc) up (region, country, factory)? Who Who will operate Language, safety and What Why How the equipment? What will be processed by the equipment? Why does the customer need the equipment? How to use the equipment? operability of equipment Feature of workpiece (before and after processing) Processing type (e.g., cutting) Productivity, safety, ease of maintenance Moreover, customer requirement description items are also listed up by referring to both Shino s 18 product development evaluation items [8],[9] and the definition of IEEE recommended practice for software requirements specification (hereafter SRS) [10][11]. Finally, these listed requirement description items are grouped into the following six fields by the grouping procedure of the KJ-method: Workpiece Equipment function Equipment production performance Production environment of the equipment Equipment purchase constraints Equipment maintenance and recycling In this paper the former four fields that relate to the basic requirements for processing are focused on. Moreover, description items relating to the equipment s function are divided into main function (processing) and auxiliary function (support functions for processing). Consequently, the following five categories will be used for listing customer requirements hereafter: (1) Workpiece/material (2) Main function (3) Auxiliary function (4) Productivity (5) Production environment A workpiece can be composed of raw materials or semi-processed parts. Requirements for a workpiece include information on the shape, dimensions, material type and accuracy of the processing performance (e.g., the roughness of the processed surface). As a large number of machining methods are available; e.g., cutting and rolling, the type of machine that a customer prefers to use is explained by its main function requirements. In addition, other functions, e.g., tool change and transport, are included in the auxiliary function requirements. The examples of the requirements for productivity include the quantity per unit time and the number of workpieces that a machine can process at one time. The production environment includes the information on space limitations for installing a machine, power voltage, etc. 2.3 Definition of Product Physical Specification Here, the literature related to product development is reviewed. For instance, Shino and Hashizume [8],[9] listed six factors for designing a machine tool (e.g., technical factors and economic factors). Taking these factors into consideration, they proposed 15 basic parameters for product specification descriptions. Further, catalogs for different types of 622 J Jpn Ind Manage Assoc

4 equipment are investigated for listing the product physical specifications. Product specifications that are listed in these catalogs and the literature are picked up and grouped into the following three categories by the grouping procedure of the KJ-method: Product formation Product performance Production environment In order to confirm the practical use of the proposed customer requirement and product physical specification categories, case studies on mixers and drilling machines are conducted. 3 CASE STUDY ON MIXERS 3.1 Case Study Description First, a mixer is selected for verification as its structure is simple and its function is relatively easy to understand. A mixer is a type of agitation equipment whose aims are to uniformly mix miscible liquids, disperse a gas through the liquid, suspend solid particles or promote heat transfer. For the sake of simplification, a mixer to uniformly mix liquids is used for the case study. Figure 2 shows an image of a mixer. Normally, it consists of the following four units: the drive unit, shaft, impeller and vessel. Fig. 2 Image of a mixer 3.2 Customer Requirement and Product Physical Specifications for Mixers Referring to the categories proposed in section 2, 10 customer requirement specifications and 12 product physical specifications are proposed (Tables 2 and 3). Table 2 Customer requirement specifications Category Specifications Code Workpiece/Material Liquid viscosity (Pa s) x 1 Liquid density (Kg/m 3 ) x 2 Main function Agitation purpose x 3 Auxiliary Protection construction* x 4 function Productivity Maximum agitation volume x 5 per unit time (l) Production Power voltage (V) x 6 environment Power frequency (Hz) x 7 x 8 Floor space (Length) ( mm) Floor space (Width) (mm) x 9 Height (mm) x 10 (*The protection construction in Table 2 describes whether there are any needs such as for explosionproofing, corrosion-proofing and so forth.) Table 3 Product physical specifications Category Specifications Code y Product Total size (mm) 1, y 2, y 3 formation (length, width, height) Vessel size (mm) y 4, y 5 (diameter, height) Impeller type y 6 Protection structure for motor y 7 Product Maximum rotation speed (min 1 ) y 8 performance Maximum agitation volume (l) y 9 Maximum agitation power (W) y 10 Production Power voltage (V) y 11 environment Power frequency (Hz) y Translation of Customer Requirements into Product Physical Specifications It is obvious that some product physical specifications can be directly obtained from the customer requirements; e.g., the power voltage y 11, frequency y 12, protection structure for motor y 7, and maximum agitation volume y 9. However, others need to be determined by referring to both the customer Vol.64 No.4E (2014) 623

5 specifications requirements and the product physical specifications. For example, the impeller type can be decided if the liquid viscosity x 1 and the maximum rotation speed y 8 are known [12]. The maximum agitation power y 10 can be calculated if liquid viscosity x 1, density x 2, maximum rotation speed y 8, maximum agitation volume y 9 and the component specifications of a candidate impeller (diameter, height of impeller blade and number of blades) are known [12]. Further, some of the customer requirement specifications are constraints for determining the product physical specifications; e.g., the total height y 3 should be lower than x 10. Through a literature survey, the proposed customer requirement specifications are proved to have sufficient information for the manufacturer to design the mixer [12]-[15]. 4 CASE STUDY ON DRILLING MACHINES 4.1 Case Study Description Next, a relatively complex product, a drilling machine is selected for the case study. 4.2 Customer Requirements and Product Physical Specifications for Drilling Machines On the basis of the categories proposed in section 2, 25 customer requirement specifications and 30 product physical specifications are proposed (Tables 4 and 5). Table 4 Customer requirements specifications Category Items Code Workpiece/Material Maximum length (mm) x 1 Maximum width (mm) x 2 Maximum thickness (mm) x 3 Material type x 4 Hole size (mm) x 5 Total moving distance x 6 along X-axis (mm) Total moving distance x 7 along Y-axis (mm) Number of holes x 8 Roughness of the inside x 9 wall (±µm) Accuracy of the hole position (±µm) x 10 Main function Processing method x 11 Auxiliary Workpiece supply x 12 function Tool exchange x 13 Tool breakage detection x 14 Tool stock capacity x 15 Fig. 3 Image of a drilling machine Figure 3 shows an image of a drilling machine. Usually, a drilling machine is composed of the following five units: table, the table s drive unit (in this case, only the X-axis), processing component, the processing component s drive unit (in this case, both the Y-axis and the Z-axis) and the bed. Productivity Number of stations x 16 Processing quantity per unit time Number of stacked workpieces each time x 17 x 18 Production Power voltage (V) x 19 environment Power frequency (Hz) x 20 Room temperature ( C) x 21 Room humidity (%) x 22 Floor space (Width) ( mm) x 23 Floor space (Length) (mm) x 24 Maximum floor load (kg/ m 2 ) x J Jpn Ind Manage Assoc

6 Table 5 Product specification description parameters Category Description parameter Code y Product Total size (mm) 1, y 2, y 3 formation (length, width, height) y Table size (mm) (length, width) 4, y 5 Product performance Production environment Gross weight (kg) Color Drill type Drill size (mm) Number of cassette holes Number of stations Maximum chuck diameter of main shaft (mm) Travel distance of X-axis (mm) Travel distance of Y-axis (mm) Travel distance of Z-axis (mm) Maximum X-axis feed rate (mm/min) Maximum Y-axis feed rate (mm/min) Maximum Z-axis retraction rate (mm/min) Maximum Z-axis cutting feed rate (m/min) Spindle speed (k rpm) Tool exchange method Broken drill bit detector Feed method Positioning accuracy (±mm) Air pressure of stand-alone vacuum (m 3 /min) Roughness of inside wall (±µm) Power voltage (V) Power frequency (Hz) Room temperature ( C) Room humidity (%) y 6 y 7 y 8 y 9 y 10 y 11 y 12 y 13 y 14 y 15 y 16 y 17 y 18 y 19 y 20 y 21 y 22 y 23 y 24 y 25 y 26 y 27 y 28 Y 29 y Translation of Customer Requirements into Product Physical Specifications Each of the product physical specifications is checked to see if it is related to any of the proposed customer requirement specifications. Moreover, discussions are conducted on whether there are any unnecessary or omitted specifications. Based on the discussion with the engineers of the product development department of firm B, it is clarified that there are three kinds of equations to calculate the product specification parameters. The examples are shown in Eqs. (1)-(3). Additionally, there exist two types of constraints among product specification parameters and customer requirement items. [Type 1] The value of a product specification parameter depends on one variable, e.g., the table width depends on the width of a workpiece. C 1 is a constant. y 5 x 2 C 1 (1) [Type 2] The value of a product specification parameter depends on two variables, e.g., the length of the equipment depends on two variables, the length of the workpiece and the number of stations. y 1 x 16 (x 1 C 1 ) C 2 (2) [Type 3] In addition, a more complicated relationship exists among product specification parameters and customer requirement items. For example, supposing the X, Y, Z-axis and drill are independently moved in sequence, the maximum X-axis feed rate can be calculated using Eq. (3). x6 y16 60 x7 x3 x8 x18 x3 x8 x18 x17 x18 y17 y18 y19 (3) The following are examples of the two types of constraints between customer requirement specifications and product physical specifications. Vol.64 No.4E (2014) 625

7 [Size constraint] For example, there are size constraints between the floor space (length) x 24 and the total length of the equipment y 1. [Mechanical strength constraint] This is a constraint for avoiding damage or rapid deterioration. For example, a drill will break if its size is considerably smaller than the thickness of a workpiece. Interviews were conducted at an ETO firm to clarify the practical use of the proposed customer requirement specifications. A case study was conducted, and it was clarified that customer needs could be gleaned and converted into detailed product specifications by the proposed items. 4.4 Effect of the Proposed Customer Requirement Description Model In order to confirm the effect of the proposed customer requirement description model, the historical inquiry data of product category N at firm B is investigated. Figure 4 shows the result of the investigation. Before the proposed model is used at the inquiry stage, an average of 3.2 days was required for the firm to finally master the customer s requirement and provide the quotation. As a comparison, it is reduced to 2.1 days per inquiry after the proposed model is used (Day) Before After Fig.4 Average days required for quotation 5 CONCLUSION AND FUTURE DIRECTIONS In order to obtain more orders and provide products within a short period of time, it is important to understand customers requirements at an early stage. This study indicates that it is not efficient to acquire customer requirements on the basis of the product specifications obtained from the design/engineering department (which we call the product physical specifications). Instead, customer requirement specifications are proposed. This study considered mixers and drilling machines as examples. Detailed customer requirement specifications and product physical specifications were designed for these two kinds of products. Further, the relationships between the two types of specifications were discussed. Through interviews conducted at equipment manufacturers and a literature survey, the proposed customer requirement specifications were proven for practical use. Therefore, the effects on efficiently acquiring orders and reducing financial loss can be expected. Many further studies should be conducted, such as customer requirement description from the viewpoints of maintenance and purchase constraints, demonstrations on various production equipment types and so forth. Moreover, since an ETO firm needs to produce various customized products, there are a large number of possible part/component candidates. With the consideration of part costs and part inventory costs, the value design for each product physical specification is also a critical factor. ACKNOWLEDGMENTS This work was supported by MEXT KAKENHI Grant Number , a Grant-in-Aid for Scientific Research (C). REFERENCES [1] Nakano, T., Noguchi, K. and Kyoya, Y.: The Design Support Tool to Set Up the Target Specifications Based on the Customer Requirements, Jpn. Soc. of Mech. Eng., No , pp (2001) [2] Xu, Q., Jiao, R., Yang, X. and Helander, M.: Customer Requirement Analysis Based on an Analytical Kano Model, Proceedings of the 2007 IEEE IEEM, pp (2007) [3] Xie, H., Henderson, P. and Kernahan, M.: Modeling and Solving Engineering Product Configuration Problems by Constraint Satisfaction, Int. J. Prod. Res., Vol. 43, No. 20, pp (2005) 626 J Jpn Ind Manage Assoc

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