Precision and durability are critical in plastic injection moulding, where even the slightest imperfections in moulds can lead to defective parts and operational inefficiencies. Traditional mould repair methods, such as thermal spray coatings or laser cladding, introduce heat-affected zones (HAZ), altering the mould's microstructure and leading to residual stresses, distortions, or phase transformations.
To eliminate these challenges, Vidhata Plastics, a leading plastic injection mould manufacturer in India, has integrated Cold Spray Technology in mould repairing, an advanced solid-state deposition technique that restores moulds without altering their metallurgical properties. This blog provides a deep technical analysis of how Vidhata Plastics employs Cold Spray Technology, its process parameters, and its critical role in achieving high-precision mould restoration.
The Metallurgical Challenges in Mould Repair
Moulds used in plastic injection moulding are typically made from high-performance tool steels (H13, P20, D2) or hardened stainless steel grades. These materials offer excellent wear resistance, thermal stability, and toughness. However, continuous exposure to high-pressure molten polymer injection, cyclic heating, and abrasive wear cause localized material degradation, leading to defects such as:
Micro-cracks and fatigue wear from repeated thermal cycling.
Cavitation and erosion in high-pressure moulding zones.
Pitting corrosion in aggressive polymer processing conditions.
Surface oxidation and delamination from long-term operational exposure.
Conventional repair techniques, such as TIG welding or thermal spraying, introduce heat-induced residual stresses, leading to carbide precipitation and grain coarsening, which compromise mould durability. Cold Spray Technology, in contrast, is a solid-state deposition method that eliminates these issues by depositing material without melting.
Cold Spray Technology in Mould Repairing: Technical Breakdown
1. Fundamentals of Cold Spray Deposition
Cold Spray is a supersonic kinetic deposition process where metallic or composite powder particles (typically 5-50 μm in diameter) are accelerated to high velocities (500–1200 m/s) using a pressurized carrier gas (Helium or Nitrogen). Upon impact, these particles experience severe plastic deformation, forming a mechanically bonded, dense coating without phase transformations.
2. Process Parameters Critical to Mould Restoration
Vidhata Plastics optimizes several cold spray parameters to achieve superior mould repair:
a. Powder Material Selection & Microstructure Control
Base Material Compatibility: High-speed steel (H13), martensitic stainless steel, and nickel-based superalloys are selected based on the mould’s substrate composition.
Particle Morphology: Spherical or irregular powder morphologies impact deposition efficiency; Vidhata Plastics utilizes gas-atomized powders with controlled size distribution for optimal adhesion.
Nanostructured Powders: For enhanced wear resistance, nanostructured carbide-reinforced coatings (e.g., WC-Co, TiC-Ni) are incorporated into cold spray formulations.
b. Carrier Gas Selection and Velocity Optimization
Helium vs. Nitrogen: Helium achieves higher velocities (>1000 m/s) for denser coatings, while nitrogen is used for cost-effective applications with moderate bond strength.
De Laval Nozzle Geometry: A converging-diverging nozzle design ensures precise acceleration of particles, minimizing rebound losses and maximizing deposition efficiency.
c. Deposition Kinetics and Bonding Mechanism
Adiabatic Shear Instability: The high-velocity impact causes localized shear instability at the particle-mould interface, resulting in strong metallurgical bonding without melting.
Cold Work Hardening: The severe plastic deformation refines grain structures, enhancing the hardness and mechanical properties of the repaired zone.
Vidhata Plastics' Cold Spray Repair Process
1. Pre-Treatment & Surface Preparation
Before deposition, Vidhata Plastics follows a strict pre-treatment protocol:
Abrasive Blasting: High-purity alumina or silicon carbide abrasives roughen the mould surface to increase mechanical interlocking.
Ultrasonic Cleaning: Removes oxide layers, contaminants, and polymer residues.
Profilometry Scanning: 3D laser scanning maps defect depth and determines the exact repair volume.
2. Cold Spray Deposition Execution
Controlled Spray Passes: Multi-layer deposition with precise pass overlap ensures uniform thickness without porosity.
Thermal Expansion Compensation: Real-time thermal monitoring compensates for slight thermal expansion effects, maintaining dimensional accuracy.
Real-Time Deposition Monitoring: Advanced in-situ diagnostics, including infrared thermography and laser Doppler velocimetry, ensure optimal impact energy for strong adhesion.
3. Post-Processing and Surface Refinement
Cryogenic Stress Relief: Low-temperature cryogenic treatment minimizes residual stresses from cold work hardening.
Precision Grinding & Polishing: Achieves Ra < 0.1 µm surface finish, critical for injection mould cavity smoothness.
Metallurgical Cross-Section Analysis: Ensures homogeneity, absence of porosity, and coating adhesion strength exceeding 100 MPa.
Benefits of Cold Spray in Mould Repair
1. Preservation of Base Material Properties
Unlike laser cladding or welding, Cold Spray Technology does not alter the mould’s hardness or microstructure. This ensures:
No phase transformation or carbide redistribution.
No HAZ-induced brittleness.
Original mould mechanical properties are retained.
2. Enhanced Wear and Corrosion Resistance
Cold-sprayed coatings at Vidhata Plastics exhibit:
Hardness up to 1100 HV (for ceramic-reinforced composites).
<1% porosity, ensuring dense, impermeable surfaces.
Coefficient of friction reduction by 30-40%, improving polymer flow during moulding.
3. Dimensional Accuracy and Tolerance Retention
Since the process involves micron-level precision, repaired moulds retain their original dimensions without requiring extensive post-machining.
4. Extended Mould Life and Cost Efficiency
Vidhata Plastics has documented:
50% reduction in mould replacement costs by prolonging lifespan.
70% decrease in repair turnaround time compared to traditional methods.
Vidhata Plastics: Redefining Mould Repair with Cold Spray Technology
As a leader in plastic injection mould manufacturing in India, Vidhata Plastics integrates Cold Spray Technology in mould repair with a data-driven approach. Real-time process monitoring, material characterization, and performance validation ensure unmatched precision and durability in mould restoration.
With a dedicated R&D team, Vidhata Plastics continuously refines deposition parameters, expands material compatibility, and pioneers hybrid repair methodologies combining Cold Spray with micro-milling and laser structuring.
Conclusion
Cold Spray Technology represents a paradigm shift in mould repair, eliminating heat-induced defects while achieving superior wear resistance and dimensional accuracy. At Vidhata Plastics, the integration of Cold Spray Technology in mould repairing is not just an innovation but a meticulously engineered solution that enhances productivity, mould longevity, and product consistency.
As a trusted plastic parts manufacturer in India, Vidhata Plastics remains at the forefront of precision mould maintenance, setting new benchmarks in plastic injection mould manufacturing in India through cutting-edge cold spray applications.
Visit Our Website: https://www.vidhata.co.in/
Contact Us: https://www.vidhata.co.in/contact
Email Id: info@vidhata.co.in
WhatsApp No. : +919550665666
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