coatings for jobbing iron and steel - foundry-planet …...prone areas pre-treated with penetration...
Post on 26-May-2020
10 Views
Preview:
TRANSCRIPT
The latest development in coatings for heavy iron and steel castings
Tim BirchInternational Marketing Manager – Foseco International Ltd
Introduction
Product development for heavy iron and steel castings Fast dry water-based coatings Duplex Coating Single-layer flow coat application
The need for control Automatic control of density Effective mixing and coating homogenisation
Content
Introduction to Total Coatings Management
Identifying the needs of the market
Investment in R&D to fulfil the needs of the foundry customer: Increase capability to produce complex, defect-free castings Improve productivity and reduced re-work Reduce overall costs
Specialised testing equipmente.g Rheometry,
Molten metal facilities,SEM
£4.5 million investment in new Foundry R&D Facility (2014)
Total Coating Management
End-to-end process control
Delivering Quality & Consistency at all process stages…..
…To ensure optimum performance at our Customers.
R&D - Delivering new products for heavy iron and steel castings
• Fast dry water-based coatings• Duplex Coating• Single-layer flow coat application
New Products
New Process TechnologyNew Raw Materials
• Automated control• Improved mixing
Fast Dry Water-Based Coating – Northern Europe Case Study
Drying of Larger Components
For larger sized components the coating is applied by flow application
• Historically alcohol based systems are used and flamed-off for quick drying
• Health and Safety Issues arise
Release of VOC’s into the environment Respiratory issues relating to solvents Restrictions on storage and use of flammable products ATEX or equivalent certification for associated equipment
Solvents – Health, Safety and Environmental Issues
Ref: European Chemical Agency Website
Improved environmental benefits through elimination of solvents Reduced surface cracking of mould due to heat generated in flame-off Reduced burn-out of coating binder
BUT : air drying is significantly longer
Benefits of water-based products
SEMCO FDC - a new range of water-based coatings for flow coating High solids content, with significantly less water to be evaporated off New rheological system allows excellent flow coating at higher solids
Layer build equivalent to a traditional coating (zircon, al-silicate or olivine fillers) Elimination of runs and drips Excellent casting performance
Faster drying water-based products
3 hour (75% solids)
5 hour (65% solids)
Drying time at 25oC (RH=60%)
When used in combination with drying oven fast drying water-based coatings deliver: Improved productivity Reduction in drying energy requirements
SEMCO FDC – improved productivity and energy saving
Oven temperature set to 61oCSEMCO FDCWLT 275 – 300μ
StandardWLT 325 – 350μ
Equivalent dry layer thickness
SEMCO FDC – improved productivity and energy saving
Surface Temperature / Moisture ContentTime in Oven Standard Coating SEMCO FDC0 minutes 25°C / 3.9% 25°C / 3.1%3 minutes 29°C / 3.7% 36°C / 0.7%6 minutes 40°C / 0.8% 48°C / 0.0%9 minutes 46°C / 0.4%12 minutes 48°C / 0.1% DRY
DRYResults50% reduction in drying time50% reduction in energy
SEMCO FDC – improved productivity and energy saving
Duplex Coating – North American Case Study
Duplex Coating System
For the prevention of metal penetration and burn-on Specifically hot spot areas Undercuts where sand compaction is not optimum
Examples of burn-on and severe metal penetration
Duplex Coating System
Prone areas pre-treated with penetration coating Fine zircon flour based coating (water or solvent based) Penetrates into surface of mould (3-5mm) Minimal surface layer build-up Completely fills all voids between sand grains
Mould then coated with traditional coating (water or solvent-based) Flow coated Brushed etc…
If there is a failure of the surface coating layer in critical areas: Mould beneath completely sealed No voids between sand grains for metal to penetrate High refractory material prevents interaction with silica sand
Duplex Coating System
Case Study 1: NORAM – Iron Jobbing Foundry
Significant problem with burn-on and metal penetration on large floor moulds.
Severe metal penetration and burn-on
WithHOLCOTE Z-Primer
(SEMCO 9223)
Clean casting
Note: Top coat is HOLCOTE 950(al-silicate coating)
Case Study 1: NORAM – Iron Jobbing Foundry
Case Study 2: NORAM – Steel Foundry
Problem – significant metal penetration in flange area
Solution – ISOMOL Z-primer (TENO ZKPX)• Brushed in critical areas• Penetration 3-5mm
Top coat - ISOMOL 578-85 (brushed) 2 layers (zircon based coating) Flame Dried between layers
Casting Results Dramatic improvement in casting finish Metal penetration and burn-on eliminated
Converted floor molding coatings to the duplex coating technology
Case Study 2: NORAM – Steel Foundry
Single Layer Flow Coating for Jobbing Foundries
For larger moulds and cores Need to apply multiple coating layers to build-up required layer
thickness (>300um)
Productivity issues arise: Time for multiple applications Availability of crane Time to use crane (multiple times)
Casting quality issues: If done incorrectly the coating layers may de-laminate Brushing leads to inconsistency in layer and brush-marks
Single Layer Flow Coating for Jobbing Foundries
24
New rheological system allows for: Thick layer (>700um) to be applied in one application Consistent layer build from top-to-bottom of mould surface No slumping No runs and drips No cracking on drying
Casting performance equivalent to that achieved with multiple-layer application
Single Layer Flow Coating for Jobbing Foundries
2/03/2017 Footnote
25
26
Flow tests
A wide variety of flow characteristics can be obtained by modifying the formulation
Applied wet layer: 1000 μm
Example – dry layer achieved on furan cores
27
Dry layer≈ 1050 μm
Dry layer≈ 830 μm
Hexagon Block – Steel Casting
28
28
• Casting weight: ≈ 125 kg• Six different coatings
29 29
Casting Comparison
bottom (ingate) top
R962Single layer thick coating
top layer: ≈ 850 μm
29
SemcoCoat 9223 +SemcoZir 7300B (1x)
top layer: ≈ 450 μmpenetration ≈ 5mm
In-house casting trials with steel
Casting design (severe conditions)• Cast weight approx. 210 kg• Increased core length
Magma simulation• Longer solidification times (≈ 53 min – 65 min)
#1
#4
#3
#20,0
20,0
40,0
60,0
80,0
100,0
1400,0
1440,0
1480,0
1520,0
1560,0
1600,0
0,0 10,0 20,0 30,0 40,0 50,0 60,0 70,0 80,0
Degree of solidificatio
n [%]
Temp
erat
ure
[⁰C]
Time [min]
Simulation of hexagon test casting: solidification and core temperature
Core #1 Core #2
Core #3 Core #4
maximum T steel around core#1 maximum T steel around core#3
Degree of solidification [%]
Tliquidus≈ 1520 ⁰C
Tsolidus ≈ 1470 ⁰C
Awaiting casting results
Effective Mixing and Coating Control
The effectiveness of a specific coating is controlled by the applied dry layer thickness
Too thin and the coating is not effective Too thick and material is wasted, plus risk of: Dimensional issues Scabbing Excessive runs and drips etc…
Wet layer thickness is a good proxy for dry layer
Measurement of dilution and adjustment
32
Traditionally the application parameters for foundry coatings are defined by Baume or Flow Cup viscosity – related to applied layer
Both methods open to operator interpretation Measurement technique Supplier of measurement device (specifically Baume) Local standards (DIN, Ford, ISO etc..)
Baume vs. Flow Cup
33
Lowest actual Baume = 24 275um Highest actual Baume = 30 440um
Layer Thickness variation
34
Lowest actual Viscosity = 13.5 sec 260um Highest actual Viscosity = 16.5 sec 410um
Baume Flow Viscosity
These measurements attempt to measure the combined influence of Solids Content (or dilution) Rheological effect of the gel For Baume – termed “Body” For Flow Cup – the viscosity
If we eliminate the need to measure rheology…. Batch-to-batch consistency from supplier Correct homogenisation of product
….An improved measurement technique can be adopted.
The Limitations of Baume and Flow Viscosity
35
Flow cup and Baume incorporate the coating rheology into the measurement
If we have consistency of rheology from the supplier Density becomes the most effective measurement
Density measurement variations
36
Density measurement of a coating
Density measured in range of +/- 0.004 g/ml
With variation of +/- 0.004 g/ml Variation in applied layer of +/- 10um
Automatic Density Measurement Proven method of continuous density measurement Provides coating density measurement to 3 decimal places Complete homogenisation of the prepared coating
Continuous Density Measurement
37
Coating density versus time Courtesy: Atlantis Foundry (Halberg), S.Africa
Minimise scrap and re-work in the most cost effective manner
Ensure the coating you use is rheologically stable with time Apply most protection where it is needed – Z-Primer Improve your productivity
Fast drying water-based products Single layer flow coating to high layer thickness
Reduce your energy consumption Fast drying water-based products
Ensure you apply a sufficient protective layer every time Automated density control and coating homogenisation
Conclusions
2/03/2017 Footnote
38
Questions
39
Thank-you for your attention
Acknowledgements: Christoph Genzler Europe - Product Manager (Coatings)Bruce Lundeen North American - Product Manager (Mould & Core)Martien Haanepen R&D Scientist
top related