Thermal Distortion Testing

Transcription

1 Thermal Distortion Testing Sam Ramrattan Department of Engineering Design, Manufacturing and Management Systems Western Michigan University

2 Thermal Distortion Testing (TDT) The expansion, contraction, and degradation experienced by a mold/core under extreme heat and liquid pressure of the molten metal Effects: Expansion oversized castings Distortion penetration, veins / rat tails

3 Consequence of Problems Rat Tail Penetration

4 TDT - Stresses on Specimen

5 TDT Measurements

6 TDT

7 Effect of Compression and Tension Forces on a Sand Disc Specimen Before TDT After TDT (White unbounded sand) After TDT (Tensile crack present after 10psi blow) After TDT (Back Side) Hairline Crack

8 Samples Before Elevated to Temperature After TDT (Blown with 10psi) As-Cast Compression Surface As-Cast Tension Surface SHL Vein PUCB Penetration FUR AIO

9 TDT Curves Reminder: Percent binder and sand type held constant

10 Old Disc Concerns Density histogram and XRCT image Non-uniform specimen density

11 Old Disc Specimens Uncoated Disc Disc refractory coated at 34% solids Raised Parting Line

12 Old Disc Tooling Three-cavity core box Vertically parted Two vents per cavity

13 New Disc Tooling Three piece tool to avoid raised parting line on test surfaces - Inserts can be of different thicknesses Distributed venting to reduce density variation Layout with radial symmetry to reduce cavity to cavity specimen variation Simple shape allows for easier addition to tooling

14 New Disc Tooling Three-piece tooling for new disc specimens

15 New Disc Tooling - Insert Radial symmetry Flat faces on testing features Parting line venting applied to disc perimeter

16 New Disc Tooling Specimens Tree of disc specimens produced in new tool

17 Simulation Core Blowing Volume Fraction

18 Simulation Predicted Specimen Density

19 Simulation Core Blowing Air Velocity Vectors

20 Simulation Core Curing Curing Front Progression

21 Testing parameters: Old vs New tooling specimens Same test conditions Control of specimen recipe - Same sand - WI, 65 AFS/gfn, Round Same binder system Same binder level - 0.9%

22 Results

23 Results

24 Results

25 Results

26 Results

27 Displacement Identifying time till crack occurrence 0.14 Raidial movement Time

28 Map & Measure the HAZ

29 Image Analysis Sample - Before Test Sample - After Elevated Temperature Exposure Displacement Composite Overlay

30 Measurement of As-Cast Defects SHL Vein: Max Height 0.02in PUCB Penetration: Max Height 0.061in Note: Neutral Surface Determined from Pretested Specimen Surface

31

32 Coating Properties Measurement Coating % Solids Surface Tension [7.5 sec to equilibration] (Dyne/cm) Ct1 (0.35% Surfactant) Ct3 (0.15% Surfactant) 38% ±0.01 ± % ±0.01 ± 0.77 CastExpo 10 March 20-23, 2010 Orlando, FL USA

33 Differences in Sand Distribution

34 before TDT Results after TDT (0.14MPa) (coated side) after After TDT (0.07MPa) (back side)

35 Longitudinal Distortion / mm plastic deformation expansion 0.1 uncoated disc 42% sol. 38% sol. 34% sol. 0 Time / sec

36 What is the effects of blends and additives?

37 Green Sand TDT Specimen

38 Casting Trial Stress on Specimen

39 Casting Trial: Compression/Tension Model

40 Casting Trial: Distortion Measurement Model Designed to mimic parameters of TDT:

41 Thank You For Your Attention

42 For additional information, please contact: Name: Sam Ramrattan Address: WMU CEAS, Kalamazoo, MI Phone: Fax: Web Site Address: wmich.edu/edmms/