New design for assembly methodology adapted to large size products: Application on a solar tracker design

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Procedia CIRP 00 (2017) 000–000 Procedia CIRP 84 (2019) 468–473 www.elsevier.com/locate/procedia

29th CIRP Design 2019 (CIRP Design 2019) 29th CIRP Design 2019 (CIRP Design 2019)

New assembly methodology adapted to size products: New design design for for28th assembly methodology to large large CIRP Design Conference, Mayadapted 2018, Nantes, France size products: Application Application on on aa solar solar tracker tracker design design A new methodology to analyze the functional and physical architecture of A.Remirezaa, A.Ramosaa, I.Retolazaaa*, M.Cabelloaa, M.Camposaa, F.Martinezaa , A.Ramos , I.Retolaza oriented *, M.Cabello , M.Campos , F.Martinez existingA.Remirez products for an assembly product family identification IKERLAN Technology Research Centre, Po.J.Ma. Arizmendiarreta 2, 20500 Arrasate-Mondragon, Guipuzkoa, Spain a

a IKERLAN Technology Research Centre, Po.J.Ma. Arizmendiarreta 2, 20500 Arrasate-Mondragon, Guipuzkoa, Spain * I.Retolaza. Tel.: +34 943 71 24 00; fax: +34 943 796 944. E-mail address: [email protected] * I.Retolaza. Tel.: +34 943 71 24 00; fax: +34 943 796 944. E-mail address: [email protected]

Paul Stief *, Jean-Yves Dantan, Alain Etienne, Ali Siadat

École Nationale Supérieure d’Arts et Métiers, Arts et Métiers ParisTech, LCFC EA 4495, 4 Rue Augustin Fresnel, Metz 57078, France

Abstract

*Abstract Corresponding author. Tel.: +33 3 87 37 54 30; E-mail address: [email protected]

This paper describes a new design methodology for long life and large size (Ll-Ls) product assembly, which has been developed modifying and This paper describes a new methodology for long life and large them size (Ll-Ls) product assembly, been developed modifying and merging existing Design fordesign Assembly (DfA) methodologies to adapt to the particularities of thiswhich kind has of products. These goods are often merging existing Design for Assembly (DfA) methodologies to adapt them to the particularities of this kind of products. These goods are often formed by different large and heavy subcomponents that need to be assembled and commissioned on field, which require the use of several Abstract formed byspecial different large andaspects heavy subcomponents that need be assembled and commissioned field, which require the use of several people or machinery, that are not considered in to traditional DfA methodologies. Theon new methodology, through a Lucas-Hull people or special machinery, aspectsgives that the are chance not considered in traditional DfA methodologies. The new methodology, through DfA methodology based approach, to evaluate and enhance different design options in the design phase withouta Lucas-Hull the need to InDfA today’s business environment, the trend the towards moreevaluate product and variety and customization is unbroken. to this development, the need of methodology based approach, chance enhance different design options in Due the design needthe to construct and test prototypes, whichgives are usually quitetoexpensive for this typology of products. An in-house tool hasphase been without created the to help agile and reconfigurable production systems emerged toexpensive cope withfor various productsofand productAn families. Totool design and optimize production construct and test prototypes, which are usually quite this typology products. in-house has been created to help the designer in the evaluation of different options, where the identifications of the critical features that penalize the assembly of Ll-Ls products are systems asinwell as to choose the optimal product matches, product analysis methods are needed. most of the known methods aim are to designer the evaluation different options, where the identifications features thatIndeed, penalize the assembly Ll-Ls products easily identifiable. A case of study has been carried out over a solar trackeroftothe testcritical the new approach where design efficiencyofhas been optimized analyze a product or one product family on the physical level. Different product families, however, may differ largely in terms of the number and easily identifiable. A case study has been carried given out over solar tracker to test new that approach where design efficiency been up to 20.4 percentage points through the advices by athe methodology. Thisthe means the optimized design can save has up to theoptimized 22.8% of nature of components. This fact impedes an efficient and choice of appropriate product familydesign combinations for thethe production up 20.4 percentage points through the advices givencomparison by the methodology. thatYet, the optimized canare save up to 22.8%the of the to assembly cost in an standard 4.6MW plant, which usually has up to 850This solarmeans trackers. although the results really promising, system. A new cost methodology is proposed toplant, analyze existing products intoview of theirtrackers. functional and physicalthearchitecture. The aim is to cluster the assembly in an standard 4.6MW which usually has up 850 solar Yet, although results are really promising, the need to study and add logistic factors to the methodology for this kind of products has been proven, as involved high costs in the whole these inand newadd assembly oriented families for the existing has assembly andastheinvolved creation high of future needproducts to study factors product to the methodology foroptimization this kind ofofproducts been lines proven, costsreconfigurable in the whole installation process needlogistic to be considered assembly systems. Based on Datum Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and installation process need to be considered a functional analysis is performed. Moreover, a hybrid functional and physical architecture graph (HyFPAG) is the output which depicts the © 2019 The Authors. Published by Elsevier B.V. © 2019 2019 The The Authors. Published by Elsevier B.V. similarity between product families by providing design support to both, production system planners and product designers. An illustrative © Authors. Published by Elsevier B.V. committee Peer-review under responsibility of the scientific of the the CIRP Design Design Conference Conference 2019. 2019 Peer-review under responsibility of the scientific committee of example of a nail-clipper is used to explain the proposed methodology. industrial case study on two product families of steering columns of Peer-review under responsibility of the scientific committee of the CIRP CIRPAn Design Conference 2019 thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach. Keywords: Design for Assembly, large size products, design methodology, solar panel design ©Keywords: 2017 TheDesign Authors. Publishedlarge by Elsevier B.V. design methodology, solar panel design for Assembly, size products, Peer-review under responsibility of the scientific committee of the 28th CIRP Design Conference 2018. Keywords: Assembly; Design method; Family identification

1. Introduction 1. Introduction

factors apart from the functionality of the product are taken factors apartduring from the thepossible producttoare taken into a count the functionality design phase, of it is optimize into a count during the design phase, it is possible to optimize Assembly and installation factors are determinant in the design and reduce significantly the final cost of the Assembly and installation factors arecost determinant in the design reduce significantly final cost as ofDfX the certain types of products for the final and correct product [5,6].and The methodologies have the been extended 1. Introduction of the product range and characteristics manufactured and/or certain types of products for the final cost and correct product [5,6]. The methodologies have been extended as DfX performance and hence need to be considered when methods toin include the concept of design excellence assembled this system. In this context, thefor main challenge[7]. in performance and turbines, hence need to be considered when methods to include the concept of design for excellence [7]. designing. Wind photovoltaic power stations, DfX methodologies have been developed and improved in Due to the fast development in the domain of modelling and analysis is now not only to cope with single designing. Wind turbines, are photovoltaic power stations, DfX methodologies have beenand developed anddeveloped improved the in elevators or truss structures examples of these kinds of recent years since Boothroyd Dewhurst communication and an ongoing trend of digitization and products, a limited product range or existing product families, elevators or truss structures are examples of these kinds of recent years since Boothroyd and Dewhurst developed the products as well as construction industry. these have in firstalso DfX methodologies in and the 80s: Designproducts for Assembly or digitalization, manufacturing enterprises are All facing important but to be able to analyze to compare to define products as well astoconstruction industry. Alllong these have in first DfX methodologies inhas theshown 80s: Design formainly Assembly or common the need be assembled in place, life cycles DfA [8]. Further research that DfX, design challenges in today’s market environments: a continuing new product families. It can be observed that classical existing common the need to be assembled in place, long life cycles DfA [8]. Further research has shown that DfX, mainly design (more than 25 years) and large size parts or subparts [1–4]. for manufacturing (DfM) andin assembly a whole tendency towards reduction of product development times and product families are regrouped function of(DfA) clientsas or features. (more thanthe25chosen years)installation and large size parts are or subparts [1–4]. for manufacturing (DfM) and assembly (DfA) as assembly a whole Although resources cost significant (DfMA), has a strong influence on manufacturing, shortened product lifecycles. In addition, there is an increasing However, assembly oriented product families are hardly to find. Although the chosen installation resources are cost significant (DfMA), has a strong influence on manufacturing, assembly (cranes,of lorries, workforce)being the design and life [9] and level, thus products are the most in two the demand customization, at the itself same and timethe in decisions a global Onproduct the product family differcommon mainly in (cranes, lorries,theworkforce) the design itself and factors the decisions and product life [9] and thus are the the most common in the made during design phase are the major when industry and the ones that tend to be most impactful. In competition competitors all are overthe themajor world.factors This trend, main characteristics: (i) that the number components and (ii) the made duringwith theinstallation design phase when industry and the ones tend to of beprimarily the mostonimpactful. In determining the cost. general, these methodologies focus facilitating which is inducing the development from macro to micro type of components (e.g. mechanical, electrical, electronical). determining the installation cost. general, these methodologies focus primarily on facilitating Manyresults different methodologies developed assembly, the considering number of parts orsingle variability and markets, in design diminished lot sizes have due been to augmenting Classicalminimizing methodologies mainly products Many different design methodologies have been developed assembly, minimizing the number ofother parts or variability and during the last decades, as it have been noted that if different allow for the consideration of issues, such as product varieties (high-volume to low-volume [1]. or solitary, existing product families analyze during the last decades, as it have been notedproduction) that if different allow for already the consideration of other issues, such the as To cope with this augmenting variety as well as to be able to product structure on a physical level (components level) which identify in the existing causes difficulties regarding an efficient definition and 2212-8271 possible © 2019 The optimization Authors. Publishedpotentials by Elsevier B.V. 2212-8271 2019responsibility The itAuthors. Published Elsevier B.V.of the Peer-review©under of the scientific committee CIRP Design Conference 2019 of different product families. Addressing this production system, is important tobyhave a precise knowledge comparison Peer-review under responsibility of the scientific committee of the CIRP Design Conference 2019

2212-8271©©2017 2019The The Authors. Published by Elsevier 2212-8271 Authors. Published by Elsevier B.V. B.V. Peer-review under responsibility of scientific the scientific committee theCIRP CIRP Design Conference 2019. Peer-review under responsibility of the committee of the of 28th Design Conference 2018. 10.1016/j.procir.2019.05.002

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accessibility, handling and the need for fitting with tools [10]. It is interesting to develop general methodologies that take the nature of the product into account and facilitate the application and optimization of the benefits [11]. DfA methodologies have been widely studied for years, and appropriate design methodologies have been developed that focused on key aspects of assembly during the design phase. Another fundamental objective of these methodologies is to minimize the number of assembly operations and thus assembly time and costs. Some examples of tools with DfA methodologies used in case studies can be found in the literature [12–14]. Even more, applying DfA methodologies for large size goods, which are not usually mass produced and are highly customized, becomes challenging [15]. There is currently no efficient methodology that addresses the unique nature of these types of products where assembly becomes installation and involves bigger and more costly resources. Installation procedures are usually disregarded until logistic factors (assembly, transport, packaging, resources planning, etc.) are taken into account and the design is finished. For the most impact, this new methodology should address the abovementioned issues from a design perspective. Existing DfA methodologies are apparently the best base to start with the new methodology approach, as assembly and installation operations have similar nature have been widely studied in the state of the art. The proposed methodology adapts and merges existing DfA methodologies including many aspects that are determinant in the final cost of Ll-Ls products such as maintenance, obsolescence, logistics (transport, packaging, etc.), assembly and manufacturing. The challenge of this approach is to combine different objectives that sometimes could give conflictive solutions. This paper explains the long life and large size product new design for assembly methodology and applies it in a solar tracker case study.

The B&D DfMA methodology is usually applied on small and mass produced products and analyzes each particular operation during the assembly process while the Lucas/Hull method is a penalty-based method that focuses on three important aspects of product design and measures them with three indices: the Efficiency Index, the Handling Index and the Fitting Index [17]. Another unique aspect of the B&D DfMA methodology is the use of three questions to identify critical components. This DfA approach consists on combining these two existing methodologies and adapting them to Ll-Ls products. The most beneficial ideas to evaluate this kind of products have been selected from each methodology as follows. A modified Boothroyd and Dewhurst (B&D) DfMA method has been chosen for critical part identifications and a modified Lucas/Hull (L/H) DfA methodology for component or design features penalization and assessment. The approach is shown in Fig. 1.

Nomenclature

First step is the identification of the elements of the product to be analyzed. The product is decomposed in functional groups and then in assemblies and parts. It is determined how and where are going to be the units assembled, which ones will need especial machinery to be transported or assembled, etc. This information it is necessary for next step. Once the components that need to be studied are defined, critical parts are easily identified by B&D DfMA method. Their proposal consist on asking three questions (first three questions shown below) and if one of these answers is positive, the part is critical what means that it cannot be removed from the design. To adapt it to Ll-Ls products, more questions have been added to this evaluation (last four questions).

B&D DfA DfM DfMA DfX Ll-Ls L/H

Boothroyd and Dewhurst Design for Assembly Design for Manufacturing Design for Manufacturing and Assembly Design for excellence Long life and large size Lucas/Hull

2. New design methodology The new methodology is developed in a way that it can be easily integrated into a standard product design process (Fig.1). The new methodology is based on two well-known different DfA methodologies: B&D DfMA and L/H DfA, which are focused on reducing the number of parts and variability. Both use similar approaches to reduce the number of parts and increase the efficiency of the design. However, the B&D method is more focused on the assembly sequence, while the L/H method is more focused on the evaluation of the components themselves [16].

Fig. 1: New DfA methodology approach

1. 2. 3. 4. 5. 6.

Does it have a relative movement? Does it have a different material? Is it necessary to remove for maintenance? Is it the base part where the rest are assembled? Does it need to be separated from other parts? Is special transportation required?

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 Commissioning ratio < 2

7. Is it necessary for the correct functioning of the unit? Question number 4 is thought for the parts that are prejudicial because of its size but essential for the product; moreover, it ensures to be at list one critical part per every assembly. Question number 5 considers factors of logistics analyzed at the previous phase (e.g. if there is a maximum size for the transport, some parts cannot be combined). Question number 6 is to consider big parts where other components can be added and transported together, this way assembled time in field is shorter. The last question is a generic one that permits the designer to define a part as critical for any other reason considered. Next step of the methodology involves Lucas/Hull method. It consists on penalizing features of parts that are considered more harmful to the handling and fitting. Each attribute has a penalization punctuation gathered in some tables [18]. Values of these tables have been modified and new penalty factors have been added to fit in Ll-Ls products and its installation. Moreover, a new category called assembly has been added. It gives the opportunity to evaluate assemblies formed by individual components and other sub-assemblies and that are installed in field as a hole. Once DfA evaluation is finished, L/H method calculations are performed, the designer obtains a report and recommendations based on the calculus of three ratios: design efficiency (equation 1), handling ratio (equation 2) and fitting ratio. In this approach, instead of fitting ratio, a new composing ratio is proposed. The idea behind both ratios is the same, but it has been adequate to Ll-Ls goods, so aspects that are evaluated are slightly different. Moreover, a new ratio has been created (equation 4) to evaluate aspects of commissioning that there were not considered before. 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝

𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 = 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛 𝑜𝑜𝑜𝑜 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 =

∑ 𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻 𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖

𝐶𝐶𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 =

𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝

∑ 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝

𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 =

∑ 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝

3

(1)

To help the designer to improve the design, some effective solutions are suggested (Table 1) as in a consultative guide. By applying these solutions, the assembly of the designed product will improve. Afterward, different designs are evaluated automatically by a tool developed in IKERLAN (Fig. 2). It allows to see which changes will reduce the installation costs and increase the obtained profits.

Table 1. Suggested solutions Problem

Advice

Effectiveness

High handling ratio Weight

Remove or change material

Symmetry

Make it symmetric Make a visible mark to distinguish its orientation easier

High composing ratio Fasteners

Change fastening way Reduce number of fasteners Reduce number of components (combine parts)

Access

Make direct access possible

Alignment

Design a geometry to help aligning

High commissioning ratio Commissioning

Check commissioning procedures Reduce parts/assemblies that need to be commissioned on file.

(2) Low efficiency

(3)

Non-critical parts

Consider to remove them

*Effectiveness level:

(4)

Very effective

Effective

Originally, the target for an acceptable design was efficiency above 60% and handling and fitting ratios below 2.5. The designer should suggest modifications until reaching those values. After analyzing some examples, it is seen that this target values proposed on the L/H methodology are not suitable to Ll-Ls products. Handling need to be higher because of the size of the components, fitting (composing) need to be higher because these products need a higher number of fasteners and a lower design efficiency since the number of parts it is higher. The new target values have been defined:  Design efficiency > 35%  Handling ratio < 4  Composing ratio < 40

Fig. 2: Tool to evaluate installation process

Less effective

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3. Case study: Solar tracker A case study of a solar tracker design has been carried out with the objective of improving its design from the point of view of assembly and installation using the tool developed in IKERLAN. The conversion of solar light into electric power represents one of the most promising and challenging energetic technologies, in constant development, clean, silent, with very low maintenance costs and minimal ecological impact. Nowadays, the durability of a solar energy plant is estimated at list 10 years on average. A solar tracker is composed by modules with the biggest reflecting area as possible. For instance, the analyzed solar tracker has modules with a size of 2 m x 6 m and a weight of 80 kg. A high number of this modules are assembled next to each other in a power plant, the length of a line rich 35 meters (in an standard 4.6 MW plant, usually has up to 850 solar tracker modules). So the product that has been analyzed is considered Ll-Ls and appropriate to apply the developed methodology.

471

the fact that is the most repeated part (16 times per line) and the biggest one, so any improvement here will significantly reduce the final product cost 3.2. .DfA evaluation As an example of the work done with the whole solar tracker line, analysis of the base of the module is shown bellow (same process has been repeated with the rest of components). Since the module is the most important part of the product, it has been divided in lower-level-assemblies which are going to be factory-assembled. The structure of the module is formed by different components numbered from 1 to 4 and a subassembly called cross (Fig. 4).

3.1. Description of the solar tracker The studied solar tracker has 16 modules assembled in field on a line. Each module has 11 concave mirrors which are pointed to a collector to heat the containing fluid using solar power (Fig. 3). For the analysis, the solar tracker has been divided in seven main assemblies or functional groups:  Modules  Base structure (where the modules are assembled)  Promoter system (under the first module of the line to move all mirrors)  Counterweight (under the last module of the line to stabilize the system)  Collector  Columns between modules (to hold up the collector)  Anchorage points (to hold up the collector and weights to attach the whole structure to the floor).

Fig. 3: Solar tracker components. Modified from [19]

The collector and the structure have not been analyzed since the first one is a commercial component and the second one is civil work done by concession companies. On the contrary, special attention has been paid to the modules due to

Fig. 4: Module structure and its components Table 2. Evaluation of the structure of a module UNITS

EVALUATION

Assembly

Component

Cross

Design efficiency: 6.67%

Module structure

4 3 5 7 6 8 Design efficiency: 22.22% 1 2 Cross

Critical Parts: 15; Critical: 1 Yes No No No No No Parts: 9, Critical: 2 Yes No Yes

Handling

Composing

Comm.

Handling ratio: 18.1

Composing ratio: 342

Comm. ratio: 0

1 32 32.9 17.4 33 18.9

0 0 0 0 0 0

Composing ratio: 110.5

Comm. ratio:2

1 24.9 39.8

0 1 0

1.5 1 1.7 1 1 1.3 Handling ratio: 13.35 2.2 1.3 5.7

Rep

1 2 2 4 2 4

2 4 3

After doing the DfA evaluation, the most prejudicial parts are identified (the parts with highest composing index). In this case, the efficiencies (6.67% and 22.22%) are so low that almost all parts are considered to redesign. So, the original design (Fig. 5) needs to be reviewed. Looking at the recommendations, the designer has to suggest new design options such as remove parts or combine parts into one as follows: Three different improvements to the cross assembly (Fig. 6): a) Merge all the squares and the cross central part with the profiles. b) Eliminate the squares, the cross is made by folding a profile and the central metal sheets in a unique part. c) Squares merged with the side profiles and central metal sheets in a unique part.

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5

After evaluating manufacturability, it is seen that the best option is c.

Fig. 5: Original design of cross subassembly

a

c

b

Fig. 8: Results of efficiency of the original and optimized design

3.3. Case study analysis

Fig. 6: Three design options that facilitate assembly

Improvements to the module structure consist on combining parts long profile and the supports into one part using laser cutting procedures and sheet folding (Fig. 7). a

b

Fig. 7: (a) Original design, (b) new design Table 3. Comparison of DfA evaluation results of the module structure for different options, values before and after the optimization Parameter Number of components Critical parts Efficiency (%) Handling ratio Composing ratio Commissioning ratio

Module structure 95

Cross a 15  5

b

c 15  2

15  6 11 6.67  16.67

22

1 1

11

22.2240

6.67  20

6.67  50

18.1  4.1

18.1  2

18.1  6

342  34.8

342  31.7

342  69.8

00

01

00

13.35  4.95 110.5  67.4 20

The process has been repeated with the rest of assemblies for the whole model and totally, 18 design changes have been suggested and reevaluated. The obtained results are shown in the figure bellow (Fig. 8).

After the evaluation and the given recommendations, values of the ratios have been reduced and the efficiency has been improved by doing changes at the design following the procedure shown in the chapter 3.2. Design’s efficiency has been increased 20.4% on average. For the ratios, in the best case of handling ratio a reduction of 72%, of composing ratio a reduction of 97% and of commissioning ratio a reduction of 15%. This means that the application of the methodology brings to favorable changes at the product design. To get these results, most important criteria have been reduction of number of parts, which have been reached by combining parts and changing the assembly way in order to remove parts. There are cases where it has been possible to manufacture an assembly in only one part. Reduction of commissioning ratio is the most difficult one, sometimes for the correct functioning of the product, commissioning procedures that cannot be eliminated or changed are required. A full cost analysis has been performed taking into account real assembly times and manufacturing cost to compare the results with the proposed methodology ratios and efficiencies. A potential economical saving of 30,000€ has been estimated in a 4.6MW energy plant due to the application of the developed methodology. Savings have been estimated taking into account the improvements that could be measured. Altogether, a reduction of 20,500 parts and almost 970 hours of assembly time (significant part of the saved time is factoryassembling time) has been achieved. 4. Conclusions A methodology adapted to Ll-Ls products’ design has been developed and it has been used to carry out a case study of a solar tracker, which design has been optimized applying the methodology and related design recommendations. The developed tool has been useful to make the application of the methodology easier, perform the calculations and redesign evaluations in a fast and profitable way. In general, the methodology for Ll-Ls products achieves successful results as it helps to identify the most prejudicial parts or assemblies of the design and makes the improvement

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efficient as it focusses the designer to improve only in the most relevant elements. Moreover, it has been proven that the efficiency value and ratios proposed by Lucas/Hull are not appropriate to Ll-Ls products and values set by the authors fit better. First, the efficiency objective has been updated to a more adequate value of 35% for Ll-Ls products which has been mostly reached by all the assemblies. Then, the composing or fitting objective has been increased to 40 points. It is seen that composing ratio depends on the assembly (mostly on its number of parts) and when a high number of fasteners is required, this ratio increases heavily. So, when the obtained ratio is so far from the target (as in the example shown in 3.2), it is recommended to minimize the composing ratio only as much as possible, in order to avoid extreme measures that are not going to be carried out in reality. Regarding to handling and commissioning rates, values of 4 and 1 seem adequate to Ll-Ls products. Overall, this methodology is proved useful and has a potential to improve early designs. For the near future, more case studies should be analyzed to verify or adjust Ll-Ls adapted values of the approach. Design methodology is a topic which should be developed and enhanced to keep up with the new concept of the industry. In case of this approach, it still needs to be improved as logistic factors for these kinds of products involve high costs in the whole installation process and need to be considered. For the moment, it is seen that the methodology has a great potential to improve production and reduce costs. 5. References

[10]

C. Favi, M. Germani, M. Mandolini, Design for Manufacturing and Assembly vs. Design to Cost: Toward a Multi-objective Approach for Decision-making Strategies during Conceptual Design of Complex Products, Procedia CIRP. 50 (2016) 275–280. doi:10.1016/j.procir.2016.04.190.

[11]

K.K. Fu, M.C. Yang, K.L. Wood, Design Principles: Literature Review, Analysis, and Future Directions, J. Mech. Des. 138 (2016) 101103. doi:10.1115/1.4034105.

[12]

J.E. Owensby, J.D. Summers, Assembly time estimation: assembly mate based structural complexity metric predictive modeling, J.

[13]

S. Recalt, X. Bertschy, L. Tupin, T. Contassot, Dfma: an Hybrid Design Gather Dfm & Dfa, Researchgate.Net. (2014) 0–11.

Comput. Inf. Sci. Eng. 14 (2014) 011004. doi:10.1115/1.4025808.

https://www.researchgate.net/profile/Thomas_Contassot/publicatio n/261366198_DFMA_An_hybrid_design_gather_DFM__DFA/link s/0a85e5341866babebe000000.pdf. [14]

A.Y. Bhurat, A. Garg, G. Yadav, R. Chadhokar, Swapnil, Design for Manufacturing and Assembly of Washing Machine, Concepts, Archit. Implement. 1 (1998). doi:10.1007/978-1-4615-5785-2.

[15]

G. Wallace, P. Sackett, Integrated design for low production

[16]

Ü. Kocabiçak, Optimization of the mechanical component design using design for assembly techniques, (1999) 34–42.

[17]

Lucas Engineering Systems Ltd, Design For Manufacture and Assembly Practitioners Manual. v. 10, University Of Hull, 1993.

[18]

V. Chan, F.A. Salustri, DFA: The Lucas Method, Vincent Chan. (2003). K. De Decker, The Bright Future of Solar Thermal Powered

volume , large , complex products, (1996) 5–16.

http://oaji.net/articles/2014/1084-1415086325.pdf.

[19]

Factories, Low-Tech Mag. (2011). https://solar.lowtechmagazine.com/2011/07/solar-poweredfactories.html.

[1]

T. Wegelius-Lehtonen, Measuring and re-engineering logistics chains in the construction industry, in: Re-Engineering Enterp.,

[2]

Springer {US}, 1995: pp. 209–218. doi:10.1007/978-0-387-348766_20. M. Azambuja, C. Formoso, Guidelines for the improvement of

[3]

design, procurement and installation of elevators using supply chain management concepts, (2019). B. Aas, A. Buvik, D. Cakic, Outsourcing of logistics activities in a complex supply chain: a case study from the Norwegian oil and gas industry, Int. J. Procure. Manag. 1 (2008) 280. doi:10.1504/ijpm.2008.017526.

[4]

A. Woyte, S. Goy, Large grid-connected photovoltaic power plants, in: Perform. Photovolt. Syst., Elsevier, 2017: pp. 321–337. doi:10.1016/b978-1-78242-336-2.00011-2.

[5]

A. Herrera, Design for manufacturing and assembly application of

[6]

the design of the ah64d helicopter, in: Mesa, Arizona, 1997. U.S.A. For, G. Iii, S. Goose, An aggressive design for

[7]

manufacturing program helpedmake this bird the mostsophisticated heavy- equipment transportplane in the world, Manuf. Eng. (1996). G. Pahl, W. Beitz, Design for Quality, in: Eng. Des., Springer

[8]

London, 1996: pp. 455–465. doi:10.1007/978-1-4471-3581-4_9. G. Boothroyd, Design for assembly - The key to design for manufacture, Int. J. Adv. Manuf. Technol. 2 (1987) 3–11. doi:10.1007/bf02601481.

[9]

G.Q. Huang, Design for “X” Concurrent engineering imperatives, 2010. doi:10.1007/978-94-011-3985-4.

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