Monday, December 13, 2021

DFAM - Design for Investment Casting - Important Points

 

 Lesson 255 of IEKC Industrial Engineering ONLINE Course Notes.


Engineering in Industrial Engineering -  Machine work study or machine effort improvement, value engineering and design for manufacturing and assembly are major engineering based IE methods. All are available as existing methods.


Product Design for Manufacture and Assembly, Third Edition

Geoffrey Boothroyd, Peter Dewhurst, Winston A. Knight

CRC Press, 08-Dec-2010 - Technology & Engineering - 712 pages

https://books.google.co.in/books/about/Product_Design_for_Manufacture_and_Assem.html?id=W2FDCcVPBcAC 

Note: It is important to read the books by Boothroyd to understand the full method of DFMA. The DFMA method is to be combined with Value Analysis and Engineering to do product industrial engineering. In the note only attempt is made to make readers aware of issues raised and solutions proposed by DFMA method.


Chapter 13. Design for Investment Casting 549

13.1 Introduction 549
13.2 Process Overview 549
13.3 Pattern Materials 552
13.4 Pattern Injection Machines 552
13.5 Pattern Molds 554
13.6 Pattern and Cluster Assembly 554
13.7 The Ceramic Shell-Mold 555
13.8 Ceramic Cores 556
13.9 Pattern Meltout 556
13.10 Pattern Burnout and Mold Firing 557
13.11 Knockout and Cleaning 557
13.12 Cutoff and Finishing 557
13.13 Pattern and Core Material Cost 557
13.14 Wax Pattern Injection Cost 561
13.15 Fill Time 562
13.16 Cooling Time 562
13.17 Ejection and Reset Time 564
13.18 Process Cost per Pattern or Core 566
13.19 Estimating Core Injection Cost 567
13.20 Pattern and Core Mold Cost 567
13.21 Core Mold Cost 572
13.22 Pattern and Cluster Assembly Cost 572
13.23 Number of Parts per Cluster 574
13.24 Pattern Piece Cost 575
13.25 Cleaning and Etching 576
13.26 Shell Mold Material Cost 576
13.27 Investing the Pattern Cluster 577
13.28 Pattern Meltout 578
13.29 Burnout, Sinter, and Preheat 578
13.30 Total Shell Mold Cost 579
13.31 Cost to Melt Metal 579
13.32 Raw Base Metal Cost 583
13.33 Ready-to-Pour Liquid Metal Cost 584
13.34 Pouring Cost 584
13.35 Final Material Cost 584
13.36 Breakout 586
13.37 Cleaning 587
13.38 Cutoff 587
13.39 Design Guidelines 590
References 591

Process steps - Operations Discussed in the Chapter

13.9 Pattern Meltout 556
13.10 Pattern Burnout and Mold Firing 557
13.11 Knockout and Cleaning 557
13.12 Cutoff and Finishing 557

13.15 Fill Time 562
13.16 Cooling Time 562
13.17 Ejection and Reset Time 564

13.25 Cleaning and Etching 576

13.27 Investing the Pattern Cluster 577
13.28 Pattern Meltout 578
13.29 Burnout, Sinter, and Preheat 578

13.36 Breakout 586
13.37 Cleaning 587
13.38 Cutoff 587


_____________________



https://www.youtube.com/watch?v=2rVDJKhz3Cw
_____________________

 DESIGN GUIDELINES


The investment casting process was previously known as the "lost wax" process. Its advantage over other casting processes is its ability to produce very complex castings with fine details. Investment casting offers greater freedom in design than any other metal forming operation. Accurate and intricate castings can be made from alloys that melt at high temperature. Parts can be cast to such close tolerance that little or no machining is required.

The wax or plastic patterns will be produced by injection molding. Therefore, guidelines similar to those for injection molding  apply to the pieces of the pattern that will be used to make up the final pattern shape. Thus the pattern piece must be easily removable from its mold and the main wall should have a uniform thickness, which will minimize distortion by facilitating even cooling throughout the pattern piece. In addition, the principles of good sand casting design also apply to investment casting. For example, nonfunctional mass should be minimized to assist in providing sufficient gating to "feed" the part. Also, uniform wall sections with generous radii and fillets will assist in metal flow and reduce stress concentrations.

Separate cores can add significantly to the cost, as well as bosses and undercuts. The minimum section ranges from 0.25 to 1 mm depending upon the metal to be cast. The maximum section is approximately 75 mm.

Castings range from 0.5g to 100kg in weight, but the investment casting process is best for parts that weigh less than 5 kg. A flat parting plane for each pattern piece will help to minimize the cost.


http://americancastingco.com/blog/investment-casting-design-considerations-and-tips/

Rapid Investment Casting: Design and Manufacturing Technologies 

Christopher T. Richard, Tsz-Ho Kwok

ASME 2019 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference

August 18–21, 2019

Anaheim, California, USA

RIC (Rapid investment casting) takes advantage of the additive nature of 3D printing for pattern making which allows for more complex castings than traditional investment casting. RIC is a manufacturing process that combines the casting knowledge accumulated over five thousand years with relatively novel AM knowledge. The result is a process that can compete with newer metal AM methods with the added benefits of excellent surface finish, fatigue strength and the ability to create parts from almost any metal or metal alloy. This article will focus on research advancements in investment casting, AM and all the topics that are closely related to optimizing these two processes.

https://asmedigitalcollection.asme.org/IDETC-CIE/proceedings-abstract/IDETC-CIE2019/59179/V001T02A022/1069705

Generative design realized through investment casting instead of Additive Manufacturing at a good cost advantage.
21 October 2018

AN ANALYTICAL COST MODEL FOR INVESTMENT CASTING

DS 102: Proceedings of the DESIGN 2020 16th International Design Conference, Year: 2020

Author: Mandolini, M., Campi, F., Favi, C., Cicconi, P. and Germani, M.

https://www.designsociety.org/publication/42575/AN+ANALYTICAL+COST+MODEL+FOR+INVESTMENT+CASTING

Gating System Design Optimization for Investment Casting Process

February 2019, Journal of Materials Engineering and Performance 28(54)

Marek Brůna et al.

https://www.researchgate.net/publication/331058202_Gating_System_Design_Optimization_for_Investment_Casting_Process


REFERENCES 1. Horton, R.A., Investment Casting, ASM Handbook, Vol. 15, Casting. ASM International, Metals Park, OH, 1998. 

2. McCloskey, 1C., Productivity in Investment Casting, American Jewelry Manufacturing, Vol. 38, No. 6, June 1990, p. 32. 

3. Niebel, B.W., Draper, A.B., and Wysk, R.A., Modern Manufacturing Process Engineering, McGraw-Hill, New York, 1989. 

4. Royer, A., and Vasseur, S., Centrifugal Casting, ASM Handbook, Vol. 15, Casting, ASM International, Metals Park, OH, 1988.

Ud 13.12.2021

Pub 6.12.2021

No comments:

Post a Comment