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University of Kentucky UKnowledge Institute for Sustainable Manufacturing Faculty Sustainable Manufacturing Publications

2019 Rotary Versus Fusion Butt Welding of Plastic Pipes – Feasibility and Energy Perspective Ramsey F. Hamade American University of Beirut, Lebanon

Tarek R. Andari American University of Beirut, Lebanon

Ali H. Ammouri Lebanese American University, Lebanon

Ibrahim S. Jawahir University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits oy u.

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Repository Citation Hamade, Ramsey F.; Andari, Tarek R.; Ammouri, Ali H.; and Jawahir, Ibrahim S., "Rotary Versus Fusion Butt Welding of Plastic Pipes – Feasibility and Energy Perspective" (2019). Institute for Sustainable Manufacturing Faculty Publications. 11. https://uknowledge.uky.edu/ism_facpub/11

This Article is brought to you for free and open access by the Sustainable Manufacturing at UKnowledge. It has been accepted for inclusion in Institute for Sustainable Manufacturing Faculty Publications by an authorized administrator of UKnowledge. For more information, please contact [email protected]. Versus Fusion Butt eW lding of Plastic Pipes – Feasibility and Energy Perspective

Notes/Citation Information Published in Procedia Manufacturing, v. 33, p. 693-700.

© 2019 The Authors. Published by Elsevier B.V.

This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by- nc-nd/4.0/).

Digital Object Identifier (DOI) https://doi.org/10.1016/j.promfg.2019.04.087

This article is available at UKnowledge: https://uknowledge.uky.edu/ism_facpub/11 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect AvailableAvailable online onlineScienceDirect at at www.sciencedirect.com www.sciencedirect.com

Procedia Manufacturing 00 (2018) 000–000

Procedia Manufacturing 00 (2018) 000–000 www.elsevier.com/locate/procedia ScienceDirectScienceDirect www.elsevier.com/locate/procedia Procedia Manufacturing 33 (2019) 693–700 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia 16th Global Conference on Sustainable Manufacturing - Sustainable Manufacturing for Global Circular Economy 16th Global Conference on Sustainable Manufacturing - Sustainable Manufacturing for Global Circular Economy Rotary Friction Welding versus Fusion Butt Welding of Plastic Rotary FrictionPipes Welding– Feasibility versus and Fusion Energy Butt Perspective Welding of Plastic Pipes – Feasibility and Energy Perspective Manufacturing Engineering Societya Internationala Conference 2017, MESICb 2017, 28-30c June Ramsey F. Hamade ,2017, Tarek Vigo R. Andari (Pontevedra),, Ali H. Spain Ammouri , I.S. Jawahir Ramsey F. Hamadea, Tarek R. Andaria, Ali H. Ammourib, I.S. Jawahirc aDepartment of Mechanical Engineering, American University of Beirut, Beirut, Lebanon bDepartmentaDepartment of Industrial of Mechanical and Mechanical Engineering, Engineering, American Lebanese University American of Beirut, University, Beirut, Byblos,Lebanon Lebanon CostingcDepartment models bofDepartment Mechanical of for Engineering,Industrial capacity and University Mechanical of optimiza Kentucky,Engineering, UK LebaneseCentertion for American Manufacturing in Industry University, , Lexington, Byblos, 4.0: KentuckyLebanon Trade-off 40506-0108 cDepartment betweenof Mechanical Engineering, used Universitycapacity of Kentucky, an UKd Centeroperational for Manufacturing efficiency, Lexington, Kentucky 40506-0108 Abstract Abstract A. Santanaa, P. Afonsoa,*, A. Zaninb, R. Wernkeb According to the Plastics Pipe Institute, butt fusion is the most widely used method for joining lengths of PE pipe and pipe to PE Accordingfittings “by to the fusion” Plastics (https://plasticpipe.org/pdf/chapter09.pdf). Pipe Institute, butta University fusion ofis Minho,the most 4800-058 widely However, Guimarães, used method butt Portugal-w forelding joining is not lengths energy of-cognizant PE pipe andfrom pipe the topoint PE b offittings view “ofby a heat phase fusion”-change (https://plasticpipe.org/pdf/chapter09.pdf). fabrication method.Unochapecó, This is because 89809-000 the Chapecó, sourceHowever, of SC, heating butt Brazil-welding is external is not (heater energy plate).-cognizant The frominitial the heating point andof view subsequent of a phase maintenance-change fabrication at relatively method. high This is because (above the 200 source C for of welheatingding isof externalhigh- (heater polyethylene plate). The pipe) initial is heating energy intensive.and subsequent Rotary maintenance friction welding, at relatively on the highother temperature hand focuses (above the energy 200 C where for wel andding when of high as needed-density because polyethylene it uses pipe) electric is energy motor tointensive. generate Rotary mechanical friction (spinning) welding, onmotion the other that ishand converted focuses to the heat. energy This where and will when make as the needed case forbecause friction it uses heating electric as energy motor Abstract efficient.to generate An mechanical initial feasibility (spinning) study motion will thatalso isbe converted introduced to heat.to demonstrate This work thatwill themake resulting the case welded for friction pipe heatingjoints may as energy be of comparableefficient. An quality initial to feasibility those produced study bywill butt also fusion be introduced and to virgin to PEdemonstrate material. that the resulting welded pipe joints may be of Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, comparable quality to those produced by butt fusion and to virgin PE material. information © 2018 The Authors. based on Published a real by Elsevier basis anLtd.d, necessarily, much more efficient. In this context, capacity optimization goes©This 2012019 isbeyond8 an The open Authors. the access traditional Published article under aim by of Elsevierthe capacity CC BY B.V.Ltd.- maximization,NC -ND license (contributinghttps://creativecommons.org/licenses/by also for organization’s profitability-nc-nd/4.0/) and value. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Indeed,ThisPeer -isreview an lean open under managementaccess responsibility article under and of thecontinuous scientificCC BY-NC committeeimprovement-ND license of the (https://creativecommons.org/licenses/by 16thapproaches Global Conference suggest capacityon Sustainable optimization-nc Manufacturing-nd/4.0/ ) instead of Selection and peer-review under responsibility of the scientific committee of the 16th Global Conference on Sustainable maximization.Peer(GCSM)Manufacturing-review under (GCSM).The responsibility study of capacity of the scientific optimization committee and of costing the 16th models Global Conferenceis an important on Sustainable Manufacturing topic that deserves contributions(GCSM) from both the practical and theoretical perspectives. This paper presents and discusses a mathematical modelKeywords: for Rotary capacity Friction management Welding; Energy based Consumption; on different Fusion cos Buttting Welding models (ABC and TDABC). A generic model has been developedKeywords: Rotary and itFriction was used Welding; to analyze Energy Consumption; idle capacity Fusion and Buttto design Welding strategies towards the maximization of organization’s value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization1. INTRODCUTION might hide operational inefficiency. ©1. 2017 INTRODCUTION The Authors. Published by Elsevier B.V. Peer-reviewStrict emission under responsibility laws and organizations of the scientific such committee as the Europeanof the Manufacturing Emission StandardsEngineering and Society ACARE International (flight global)Conference 2050 2017.areStrict leading emission the world laws towardsand organizations cleaner and such greener as the energy.European The Emission efforts Standardspush industry and ACAREleaders to(flight produce global) material 2050 alternativesare leading theand worldreduce towards the environmental cleaner and impactgreener from energy. manu Thefacturing efforts operations push industry [1, 2leaders]. Thus, to shifting produce operations material Keywords:towardsalternatives leanerCost and Models; and reduce energy ABC; the TDABC; efficient environmental Capacity manufacturing Manage impactment; is fromIdle of Capacity;great manu importance.facturing Operational operations Efficiency [1, 2]. Thus, shifting operations towardsPolyethylene leaner and (PE energy) has superior efficient corrosion manufacturing and chemical is of great resistance, importance. excellent insulation properties, it is lightweight and1.Polyethylene Introductionflexible, and ( thePE )cost has ofsuperior manufac corrosionturing is and relatively chemical low resistance, [3]. Material excellent properties insulation are presented properties, in Table it is lightweight 1. and flexible, and the cost of manufacturing is relatively low [3]. Material properties are presented in Table 1. The cost of idle capacity is a fundamental information for companies and their management of extreme importance in modern production systems. In general, it is defined as unused capacity or production potential and can be measured in2351 several-9789 © ways: 2018 The tons Authors. of production, Published by Elsevieravailable Ltd. hours of manufacturing, etc. The management of the idle capacity 2351This -is9789 an open © 2018 access The article Authors. under Published the CC BYby Elsevier-NC-ND Ltd. license (https://creativecommons.org/licenses/by-nc-nd/4.0/) * Paulo Afonso. Tel.: +351 253 510 761; fax: +351 253 604 741 ThisPeer- isreview an open under access responsibility article under of the scientificCC BY-NC committee-ND license of the (https://creativecommons.org/licenses/by 16th Global Conference on Sustainable-nc Manufacturing-nd/4.0/) (GCSM) E-mail address: [email protected] Peer-review under responsibility of the scientific committee of the 16th Global Conference on Sustainable Manufacturing (GCSM)

2351-97892351-9789 ©© 2017 2019 The The Authors. Authors. Published Published by Elsevier by Elsevier B.V. B.V. Peer-reviewThis is an openunder access responsibility article ofunder the sciethentific CC BY-NC-NDcommittee of licensethe Manufacturing (https://creativecommons.org/licenses/by-nc-nd/4.0/ Engineering Society International Conference 2017.) Selection and peer-review under responsibility of the scientific committee of the 16th Global Conference on Sustainable Manufacturing (GCSM). 10.1016/j.promfg.2019.04.087

10.1016/j.promfg.2019.04.087 2351-9789 694 Ramsey F. Hamade et al. / Procedia Manufacturing 33 (2019) 693–700 2 Ramsey F. Hamade/ Procedia Manufacturing 00 (2018) 000–000

Table 1: Geometric and Material Properties of HDPE 100 [4] Property Density Stress (MPa) Elongation (%) Melt flow index Diameter, Thickness, Length, L (g/cm3) D (m) d (m) (m) 0.952 26.2 >= 350 0.48 0.063 0.0058 0.200

In addition, rotary friction welding (RFW) offers a range of significant advantages that include, an environmental friendly process with short cycle that can be used to join similar and dissimilar materials. RFW is a steady – state frictional process developed during the World War. It is used for joining parts with rotationally symmetrical surfaces. Frictional welding processes convert mechanical energy into heat at the joint to be welded. The parts are rubbed together at the joining interface under axial (normal to plane surfaces) and unidirectional circular motion. This results in frictional heating that melts the material in the joining zone. When the circular motion is stopped, the molten material solidifies under pressure, forming a weld [5, 6]. Much has been reported on appropriate RFW input parameter selection for high PE joint quality. However, little effort has been placed on reporting the energy consumption of producing welds with these parameters [6-10]. In their useful study of friction welding, the authors showed that active control of the resulting grain size and distribution is critical in achieving the desired joint strength. Active control was carried out by real-time control of the process input variables (such as speed, , torque-control schemes). In return, this allowed for control over the relevant state variables (e.g., temperature and bead size). Excellent control results have been achieved and provide solid foundations for correlating the energy consumption with selected input process parameters [10].

2. RFW PROCESS AND SEQUENCE PHASES

The RFW process is categorized into four distinct phases (Phases A, B, C, D) in Figure 1(a) represented in terms of axial displacement and temperature versus time phases (Phases I, II, III, IV), respectively in Figure 1(b). The main process parameters for spin welding are, the weld , RPM, the weld pressure, (P1, P2), and the weld time (t1, t2). One part is rigidly clamped while the other is rotated to the desired speed. At time t1, the parts are brought into contact by means of axial pressure, P1. Abrasion will first strip off the surface roughness, then parts will have full surface contact. This phase is termed ‘Solid material-friction’, where the heat generated by Coulomb friction results in a temperature increase in plastic, Phase I in Figure 1(b). Melting begins during the ‘Unsteady-state friction’ phase (Phase II) once the temperature reaches the crystalline melting point of the material or glass transition temperature. The pressure P1 causes a laterally outward flow of the molten film, which in turn results in an increase of axial displacement with time. This is followed by the ‘Steady-state friction’ phase (Phase III), in which the rate of melting equals the rate of outflow, leading to a linearly increasing axial displacement with time. The molten film continues to flow while cooling, which results in further increase in axial displacement (Phase IV) [7-8].

(a) (b) Figure 1: a) RFW processs [9] b) axial displacement vs time and temperature vs time [8]. Ramsey F. Hamade et al. / Procedia Manufacturing 33 (2019) 693–700 695 Ramsey F. Hamade/ Procedia Manufacturing 00 (2018) 000–000 3

3. FUSION BUTT WELDING HEAT CONSUMPTION ANALYSIS

Fusion butt welding may be classed as a model comprising of three phases, i) heating from room temperature, ii) steady state convection, as well as iii) conduction. The convective states correspond to heating the plate from room temperature and maintaining the heat for any given time. Conductive heat transfer resembles the contact between the heated tool and pipes, where the heat transfer coefficient of polyethylene is 0.46 [11]. Heat transfer with the environment is accounted for using a convective heat coefficient of 20 W/m2(ºC) at a constant temperature of 20 ºC [9]. In their useful study of fusion butt welding, the authors proposed optimum parameters for welding HDPE, their reported heating and complete welding cycle times were 75s and 255s respectively [12]. For comparison, a conventional plate without Teflon coating is assumed. The TP 125 product specifications provided by [13], are utilised in the calculations below. As stated, the mass of the plate is 2.13 Kg and the time to reach welding temperature is approx. 10 minutes. The plate is heated from room temperature (293K) to the required melting temperature of Tm HDPE= 493 K. The length of pipe is 105mm and is assumed to be at room temperature. Using Equations 1-4, the total consumption of heating a PE is obtained and presented in Table 2.

Phase I (Specific ): (1) Where, 𝐻𝐻 = 𝑚𝑚 ∗ 𝐶𝐶𝑝𝑝 ∗ ∆𝑇𝑇 = Energy = Mass 𝐻𝐻 ( kJ) 𝑚𝑚 (𝐾𝐾𝐾𝐾) 𝑘𝑘𝑘𝑘 𝐶𝐶𝑝𝑝 (𝑆𝑆𝑆𝑆 =𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 Temperature ℎ𝑒𝑒𝑒𝑒𝑒𝑒 𝑜𝑜𝑜𝑜 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴) = 0.91 𝐾𝐾𝐾𝐾 ∗ 𝐾𝐾

𝑇𝑇 (𝐾𝐾) A conversion constant is used to obtain the power consumption.

(2) Where, −4 𝑃𝑃 = 𝐻𝐻 ∗ 2.8𝑒𝑒 = Power Consumption

𝑃𝑃 (𝑘𝑘𝑘𝑘ℎ) Using ’s Law of Cooling [14], Phase II (Steady-State Convection): (3) Where, 𝑄𝑄 = (ℎ𝑎𝑎𝑎𝑎𝑎𝑎 ∗ 𝐴𝐴𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 ∗ ∆𝑇𝑇) ∗ 𝑡𝑡 = Convection Energy ( = Convective heat coefficient 𝑄𝑄 (𝑊𝑊ℎ)𝑊𝑊 𝑎𝑎𝑎𝑎𝑎𝑎 2 = ℎ 𝑚𝑚 ∗℃) = 2 2 𝐴𝐴𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 (𝑚𝑚 ) 2 ∗ 𝜋𝜋 ∗ (𝑟𝑟 ) = time ∆𝑇𝑇 (℃) 𝑇𝑇𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 − 𝑇𝑇𝑎𝑎𝑎𝑎𝑎𝑎

𝑡𝑡 (ℎ) Phase III (Conduction): (4) (𝑘𝑘𝑃𝑃𝑃𝑃∗𝐴𝐴𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝∗∆𝑇𝑇) = Conduction Energy 𝑄𝑄 = ∆𝑥𝑥 ∗ 𝑡𝑡 = 0.28 𝑄𝑄 (𝑊𝑊ℎ) 𝑘𝑘𝑃𝑃𝑃𝑃(𝑊𝑊ℎ) 696 Ramsey F. Hamade et al. / Procedia Manufacturing 33 (2019) 693–700 4 Ramsey F. Hamade/ Procedia Manufacturing 00 (2018) 000–000

= 2 2 𝐷𝐷 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 = 𝐴𝐴 (𝑚𝑚 ) 𝜋𝜋 ∗ ( 4 ) =Length of pipe ∆𝑇𝑇 (℃) 𝑇𝑇𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 − 𝑇𝑇𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝

∆𝑥𝑥 (𝑚𝑚) Table 2: Fusion Butt Welding Power Consumption

Phase I Phase II Phase III Total Power Consumption (Wh) 109 19 0.04 128.04

4. PROCESS PARAMETERS

Welding parameters greatly influence the final weld quality; thus, an appropriate selection of parameters is critical in achieving the desired weld strength. [7] and [8] carefully analysed the effect of speed of rotation, axial pressure, interfacial torque and axial displacement on the final weld quality. The authors displayed that a weld factor of 1 for HDPE was achievable at tangential speed ( ) equal to 3.6 m/s and axial velocity close to 0.5 mm/s (red highlights Figures 2 (a) and (b). Weld strength is represented as weld factor (f), which can be obtained using equation (5) [7]: 𝑣𝑣𝑡𝑡

(5) 𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑜𝑜𝑜𝑜 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑓𝑓 = 𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑜𝑜𝑜𝑜 𝑛𝑛𝑛𝑛𝑛𝑛−𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚

(a) (b) Figure 2[8]: (a) weld factor vs tangential speed (b) axial velocity vs axial pressure

From the study [8], simplifying assumptions were used for the analysis. As shown in Figure 3 is a simple part geometry as assumed for the pipe cross section that entails an annular contact surface whose diameter is greater than the wall thickness. Weld strength is represented as weld factor (f), which can be obtained using equation (2) [7]. The data obtained from literature were utilized to develop the test matrix displayed in Table 3. The feed depth was constant at 10mm for all test cases. The tool was varied from 1224 RPM to 1884 RPM, the feed rate from 20 mm/min to 60 mm/min. Displayed below each cell is the ratio of RPM to feed rate.

Figure 3: Simple part geometry (pipe cross-section) [8] From Figure 3, the wall thickness (d) is found by subtracting the inner radius (r1) from (r2). Hence, the tangential velocity ( ) is obtained using equation (6):

𝑣𝑣𝑡𝑡 Ramsey F. Hamade et al. / Procedia Manufacturing 33 (2019) 693–700 697 Ramsey F. Hamade/ Procedia Manufacturing 00 (2018) 000–000 5

(6) Where, 𝑣𝑣𝑡𝑡 = 𝜋𝜋𝜂𝜂0(𝐷𝐷 − 𝑑𝑑) Tangential velocity m

𝑣𝑣𝑡𝑡 (min) = RPM 1 0 Diameter 𝜂𝜂 (𝑚𝑚𝑚𝑚𝑚𝑚) = Thickness 𝐷𝐷 (𝑚𝑚) = Table 3: Experimental test matrix with RPM to feed rate ratio 𝑑𝑑 (𝑚𝑚) = Feed rate (mm/min)

20 30 40 50 60

1224 (A1) (A2) (A3) (A4) (A5) 61.2 40.8 30.6 24.48 20.4

RPM (B1) (B2) (B3) (B4) (B5) 1554 77.7 51.8 38.85 31.08 25.9

(C1) (C2) (C3) (C4) (C5) 1884 94.2 62.8 47.1 37.68 31.4

5. EXPERIMENTAL

RFW was performed on the HAAS VF6 vertical machining center, which was installed with external hardware. Firstly, a work piece fixture (Fig. 2(a)) was designed to firmly mount the top half of the pipe onto the spindle head and the bottom half onto the CNC bed using a KURT vice (Fig. 2(b)). A Kistler Rotary 4-Component (Fx, Fy, Fz, and Torque ( ) Dynamometer (Type 9123C) was also attached to the spindle head (Fig. 2(b)). The Kistler 5223 B charge amplifier acquires and amplifies the emanating from the dynamometer, which is then collected by a custom LabView 𝜏𝜏 software. K-Type were utilized in order to collect temperature profiles. In addition, hall-effect transducers were tapped directly to each phase line (spindle motor and z-drive motor). This allowed for raw data acquisition that would be calibrated to obtain the motor current reading. Data of each welding operation is stored in a technical data management storage (TDMS) format that is easily accessible and requires little disk cost for data storage. More information on the set-up can be found in [10]. 91223C Dynamometer

K-Type

(a) (b) Figure 4: (a) Fabricated workpiece fixture (b) Pipe mounted to the dynamometer 698 Ramsey F. Hamade et al. / Procedia Manufacturing 33 (2019) 693–700 6 Ramsey F. Hamade/ Procedia Manufacturing 00 (2018) 000–000

6. RESULTS

Photographs of three select test cases joined at room temperature are presented in Figure 5. Visual inspections indicated that the weld bead sizes were greater for lower feed rates (Figures 5(a,c)). Color change was apparent at higher RPM (see Fig. 5(c)) which may be a result of higher temperature in the heat-affected zone. Figure 5 (b) shows some correlation between weld quality and their corresponding input parameter selection, a weld bead of negligible size can be seen for both.

(a) (b) (c) Figure 5: RFW samples at room temperature; (a) A3 (b) B3 (c) C3

Thrust (Fz) and torques collected from the dynamometer were used to calculate the axial and power consumptions for each test case. Two methods were used to calculate the power consumptions. Method 1) a conversion from mechanical work to electrical work using Equation 8. Method 2) Torques were compared to previously obtained data in order to determine the spindle motor currents, which were used in a three-phase AC motor line to ground equation. The authors noted that the relationship between the torque and current(𝜏𝜏) was 1 Nm/Amp [10]. Using the thrust forces obtained from Figure 6 in Equation 7, axial pressures were calculated. The current profile and torques obtained from Figure 7 in Equations 8 and 9 were used to calculate power consumptions. A cost comparison between the power consumptions obtained from method 2 and fusion butt welding is presented for selected values in Table 4. The price of 1 kWh in Lebanon is used, this amounts to $0.1. The depth of 10mm was achieved quicker for test cases with higher RPM and required less thrust force and torque, this is due to the achievement of the melting temperature quicker. Selected temperature profiles are presented in Figure 8.

(7) Where, 𝑧𝑧 Axial Pressure 𝑃𝑃𝑃𝑃 = 𝐹𝐹 /𝑆𝑆 = Force2 in Z-direction Pr (𝑁𝑁/𝑚𝑚𝑚𝑚 ) = = Area of Pipe 𝐹𝐹𝑧𝑧 (𝑁𝑁) 2 1200 𝑆𝑆 (𝑚𝑚𝑚𝑚 ) A3 B3 C3 1000 800

600

400

Thrust Thrust Force (N) 200

0 0 5 Time (s) 10 15 Figure 6: Experimental thrust forces for test cases A3, B3, C3 Ramsey F. Hamade/ Procedia Manufacturing 00 (2018) 000–000 7 Ramsey F. Hamade et al. / Procedia Manufacturing 33 (2019) 693–700 699

Method 1: (8) Where, Power 𝑃𝑃 = (𝜏𝜏 ∗ 𝜔𝜔 ∗ 𝑡𝑡)/1000 Torque 𝑃𝑃 (𝑘𝑘𝑘𝑘ℎ) = 𝜏𝜏 (𝑁𝑁𝑁𝑁𝑟𝑟𝑟𝑟𝑟𝑟) =

𝜔𝜔 ( 𝑠𝑠 ) = Method 2: (9) Where, 𝐿𝐿−𝑁𝑁 Power 𝑃𝑃 = (3 ∗ 𝑃𝑃𝑃𝑃 ∗ 𝐼𝐼 ∗ 𝑉𝑉 ∗ 𝑡𝑡)/1000 Power Factor of motor 𝑃𝑃 (𝑘𝑘𝑘𝑘ℎ) = Current 𝑃𝑃𝑃𝑃 = Line to Neutral Voltage 𝐼𝐼 (𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴) = 𝐿𝐿−𝑁𝑁 𝑉𝑉 (𝑉𝑉𝑉𝑉𝑉𝑉35𝑉𝑉𝑉𝑉) = 8 A3 Spindle motor current 7 30 B3 25 6 C3 5 20 4 15 3 10 Torque (Nm) 2 5 Motor Current (Amps) 1 0 0 0 20 40 60 0 5 Time (s) 10 15 Time (s) (a) (b) Figure 7: (a) Net RMS spindle current [10] (b) Experimental torques for test cases A3, B3, C3

Test case A3 at rotational speed of 1224 RPM and feed rate 40, experienced a maximum thrust force of approximately 1085 N at a maximum torque of around 7 Nm, which required a maximum current of 7 Amps. The maximum temperature achieved was about 250ºC, well above the melting temperature required. This was achieved in 8.5 and proves that RFW requires shorter cycle times than fusion butt welding. The thrust force and torque reach a maximum before decreasing to a constant steady-state phase.

Table 4: Axial Pressures and Power Consumption comparison between Fusion Butt Welding and RFW Fusion Butt Welding A3 B3 C3 - 0.35 0.27 0.18 : Method2 1 From Table 2: 0.0033 0.0035 0.0026 Pr (𝑁𝑁/𝑚𝑚𝑚𝑚 ) : Method 2 0.128 0.017 0.013 0.008 𝑃𝑃 (𝑘𝑘𝑘𝑘ℎ) Cost ($) 0.0128 0.0017 0.0013 0.0008 𝑃𝑃 (𝑘𝑘𝑘𝑘ℎ)

It can be seen that higher were achieved at higher RPM, this provides a great indication for further study on the effect of input parameters on heat generation to produce high quality welds. The cycle time achieved with input parameters of C3 was 12s compared to that of 13.5s for A3 and B3. This is due to quicker material softening from increased temperature, thus a feed depth of 10mm is completed quicker.

700 Ramsey F. Hamade et al. / Procedia Manufacturing 33 (2019) 693–700 8 Ramsey F. Hamade/ Procedia Manufacturing 00 (2018) 000–000

500 A3 B3 400 C3 ºC) 300

200

Temperature ( 100

0 0 5 Time (s) 10 15

Figure 8: Experimental temperatures for test cases A3, B3, C3

7. CONCLUSION

Presented in this paper is a feasibility and energy study between the conventional method for joining HDPE pipes (Fusion Butt Welding) and rotary friction welding. Fusion butt welding is classed as a heat transfer model involving three phases, i) heating from room temperature, ii) steady state convection (maintaining the heat for any given period) and iii) conduction (contact between pipes and heating plate). The total of the energy consumption of each of the phases is determined using a popular welding machine specification. Active control is carried out by real-time control on the process input variables, this allowed for data acquisition of thrust forces, torques and temperatures. Temperature profiles showed that the meting temperature is achieved in under 10 seconds and indicates that further analysis on heat generation is required to better understand the effect of the process input parameters on the weld quality. Experimental of thrust forces and torques for a test matrix that accounts for a range of spindle feeds, are used to determine axial pressures and energy consumptions. Two methods are used to determine the energy consumption and a cost analysis is developed. The cost analysis presented indicates that the energy consumption of RFW is one-tenth that of fusion butt welding. Thus, reduced environmental impacts and immense cost savings can be realized with a shift in style of welding operations from fusion butt welding to RFW.

REFERENCES [1] Acare4europe.org. (2018). About ACARE | Acare. [online] Available at: http://www.acare4europe.org/about-acare [Accessed 1 Apr. 2018]. [2] Amanat, N., James, N. and McKenzie, D. (2010). Welding methods for joining thermoplastic polymers for the hermetic enclosure of medical devices. Medical Engineering & Physics, 32(7), pp.690-699. [3] Takasu, N. (2003). Friction welding of plastics. Welding International, 17(11), pp.856-859. [4] Haykalplast.com. (2018). [online] Available at: http://www.haykalplast.com/downloads/catalogs/HaykalPlast-PeProductCatalog.pdf [Accessed 1 Feb. 2018]. [5] Troughton, M. (2008). Handbook of plastics joining. Norwich, NY: William Andrew Inc., pp.29-34. [6] Shrivastava, A., Krones, M. and Pfefferkorn, F. (2015). Comparison of energy consumption and environmental impact of and gas for aluminum. CIRP Journal of Manufacturing Science and Technology, 9, pp.159-168. [7] Crawford, R. and Tam, Y. (1981). Friction welding of plastics. Journal of Materials Science, 16(12), pp.3275-3282. [8] Tappe, P. and Potente, H. (1989). New results on the spin welding of plastics. Polymer Engineering and Science, 29(23), pp.1655-1660. [9] Alves, E., Piorino Neto, F. and An, C. (2010). Welding of AA1050 Aluminum with AISI 304 stainless by rotary friction welding process. Journal of Aerospace Technology and Management, 2(3), pp.301-306. [10] Ammouri, A. and Hamade, R. (2015). Toward an affordable automation scheme of friction stir processing. ASME 2015 International Mechanical Engineering Congress and Exposition IMECE2015, November 13-19, 2015, Houston, Texas. DOI: 10.1115/IMECE2015-53314. [11] Plasticpipe.org. (2018). R-Value and of PEX and PE-RT TR-48/2014. [online] Available at: https://plasticpipe.org/pdf/tr48-r-value-thermal-conductivity-pex-pe-rt.pdf [Accessed 20 Apr. 2018]. [12] Barber, P. and Atkinson, J. (1972). Some microstructural features of the welds in butt-welded polyethylene and polybutene-1 pipes. Journal of Materials Science, 7(10), pp.1131-1136. [13] Ritmoamerica.com. (2018). TP 125 - Heating Plates - Ritmo America. [online] Available at: http://www.ritmoamerica.com/product_single.php?id=20# [Accessed 20 Apr. 2018]. [14] Cho, Y., Hartnett, J. and Rohsenow, W. (1998). Handbook of Heat Transfer (3rd Edition). McGraw-Hill.