The Top Chinese CNC Precise Machining Partner
Custom CNC EDM Machining Services
From prototype to production, RPD Offer Fast and Cost-Effective One-Stop Rapid Prototyping Services. Free Engineer Support to Your Projects with Fast Turnaround Times. Reliability, Precision & Delivery.
- RPD Provide 24/7 Engineering Support All Year Round.
- Delivered in as fast as 3 days.
- 40+ CNC 3-Axis, 4-Axis & 5-Axis Machining Center, 10+ Swiss-type Lathes for Precision Components.
- Prototyping, Small Batch & Mass Production, No MOQ request.
- More Than 60+ Certified Materials for Choose. Offer CoCs, Material Certifications, Inspection Reports.
- CMM dimensional inspection.
- Expert DFM & process optimization
What are EDM and Wire EDM?
EDM (Electrical Discharge Machining)
A non-traditional process that uses electrical sparks to erode conductive materials.
Typical parts: Injection mold cavities, forging dies, deep ribs, square corners
Wire EDM
A precision process that uses a thin, continuously moving wire to cut conductive materials.
Typical parts: Extrusion dies, punch and die sets, gears, medical instruments, turbine blades.
Sinker EDM uses a shaped electrode for 3D blind cavities (molds); Wire EDM uses a moving wire for precise 2D through-profiles. Both machine any hardness with zero cutting force and no burrs.
What’s advantages of EDM Machining?
Excellent Precision & Accuracy
Achieves tight tolerances (±0.0001" / ±0.0025mm)
Machines Any Hardness
Can cut hardened steel, carbide, titanium materials that destroy cutting tools.
Excellent Surface Finish
Spark erosion leaves no burrs, reducing secondary finishing，Can achieve very fine finishes (Ra 0.2–0.8 µm) with multiple finishing passes.
Complex Shapes
Can produce sharp internal corners and deep narrow slots that milling cannot.
High Flexibility in Shapes
Can machine deep, narrow features (high aspect ratio) that end mills cannot reach.
No Mechanical Stress
No cutting forces, ideal for thin walls, delicate features, small parts.
EDM Capabilities
Sinker EDM
Slow but precise (20–400 mm³/min). Requires custom electrode (adds 1–3 days).
Best for complex 3D cavities, molds, sharp corners. Can run unattended for finishing, Machine any hardness, zero cutting force, no burrs.
Read More
Wire EDM
Cuts at 100–500 mm²/min (area). No electrode needed — faster setup. Can stack thin parts for higher output
Excellent for lights-out unattended operation (8–24 hours). Best for precision 2D profiles, punches, dies, gears.
Read More
Why Choose RPD?
Professional CNC Machining, sheet fabrication, Injection Molding & rapid prototyping, Professional Services, Comprehensive A-Z Solutions.
Guaranteed Quality & Rigorous Inspection
Advanced Technology & Broad Capabilities
Technical Partnership & Engineering Support
Wide Material/Project Experience
Competitive Value & Cost Optimization
Speed & On-Time Delivery
EDM Materials
EDM and Wire EDM can machine ANY electrically conductive material (hardened steel, carbide, titanium, Inconel, etc.) — Sinker EDM is best for 3D blind cavities (molds, dies), while Wire EDM is best for 2D through-profiles (punches, gears, extrusion dies, medical instruments).
Contact us to explore more materials today!
Aluminum
Features: Excellent machinability , short processing time, high yield rate Superior surface treatment capabilities Moderate material cost Light weight with high strength-to-weight ratio Widely used in aerospace, automotive, drones, medical, industrial automation. Common alloys include 2024-T351, 5052, 5083-H111, 6061-T6, 6063, 7075-T6 etc. More Metals
Stainless Steel
Features: Excellent corrosion resistance High strength and good toughness Resistant to high and low temperatures Non-magnetic, clean, hygienic Surface polishable to mirror finish (Ra ≤ 0.4 µm) Non-porous, easy to clean, resists bacterial growth， complies with FDA, food-grade, and medical-grade certifications. Common SS include SS303, SS304, SS304L, SS316 etc. More Metals
Titanium
Features: Titanium alloys offer an exceptional combination of high strength-to-weight ratio, outstanding corrosion resistance, excellent biocompatibility, and performance across extreme temperatures, making them the material of choice for aerospace, medical implants, and high-end applications. Common Titanium include Grade 2, Grade 3 etc. More Metals
Brass
Features: Brass offer exceptional machinability and excellent surface finishes. It combines good corrosion resistance, electrical conductivity, and an attractive gold-like appearance, making it ideal for precision components, valves, fittings, electrical connectors, and decorative hardware. Common Brass include C36000, C37700 etc. More Metals
Cr12MoV / SKD11
High hardness (HRC 58-62), good wear resistance, but can be brittle. Requires stable grinding to avoid surface burning
HSS
Maintains hardness even at high temperatures (red hardness). Used for cutting tools (drills, end mills, taps).
45 Steel / 40Cr
Good machinability. Grinds easily for achieving high surface finish (mirror-like).
Common Types of Surface Treatment Simple List
Contact us to explore more surface treatment opinions today!
| Surface Finish Type | Description | Services | Typical Applications / Benefits | Applicable Materials | Price |
| As machined | The state of the workpiece without any additional, specialized surface finishing or deburring treatment | CNC machining, Sheet Metal Fabrication, Injection Molding, Die Casting 3D Printing, Vacuum Casting | Suitable for products or prototypes without additional requirements for surface treatment | Metal, plastic | $ |
| Smooth | Deburring treatment | CNC machining, Sheet Metal Fabrication, Injection Molding, Die Casting 4D Printing, Vacuum Casting | Suitable for products or prototypes without additional requirements for surface treatment | Metal, plastic | $ |
| Electroplating | In an electrolyte solution, metal ions are attached to the surface of the workpiece by an electric current | CNC machining, Sheet Metal fabrication, Injection Molding, Die Casting, 3D printing, Vacuum Casting | Excellent anti-corrosion & appearance. Chrome/nickel plating provides bright, wear-resistant surface. Improves hardness, wear resistance & conductivity. | Metal | $$ |
| Anodizing | Electrochemical process generates a hard and porous oxide film on the surface of metal, usually for aluminum. | CNC machining, Sheet metal fabrication，Die Casting | High corrosion & wear resistance, excellent decoration (various colors via dye adsorption), good insulation, and ideal as a coating substrate for enhanced adhesion. | Metal | $$ |
| Powder Coating | Attach dry powder coating to the workpiece through electrostatic adsorption, and then cure at high temperature | CNC machining, Sheet metal fabrication，Die Casting | Thicker, durable, wear/impact-resistant. Solvent-free, eco-friendly, recyclable. Textures: gloss, matte, sanding, wrinkles. | Metal | $$ |
| Painting | Atomize liquid coating with a spray gun and attach it to the surface of the workpiece. | CNC machining, Sheet Metal Fabrication, Injection Molding,Die Casting 3D Printing, Vacuum Casting | The colors are infinite, theoretically any color can be blended. Relatively low cost, suitable for various shapes and sizes. | Metal, plastic, ceramic, Composite materials | $$ |
| Brushing | Forms a continuous fine texture to improve appearance, slip resistance, and reduce light reflection | CNC machining, Sheet metal fabrication，Die Casting | Highly decorative, presenting a metallic texture, able to cover small scratches, and resistant to fingerprints | Metal | $$$ |
| Sand Blasting | Mechanical treatment of workpiece surface by cleaning, roughening, or finishing using high-speed sand flow impact. | CNC machining, Sheet metal fabrication，Die Casting | Obtain a uniform matte/frosted texture, clean the surface, and improve coating adhesion. | Metal, plastic, ceramic | $$ |
| Black Oxide | It is a chemical conversion process that generates a layer of magnetic iron oxide (Fe ∝ O ₄) film on the surface of steel or stainless steel. | CNC machining, Sheet metal fabrication，Die Casting | Excellent dimensional stability, rust prevention, anti-reflective, and wear resistance (with post-processing). Provides a durable matte black finish with strong adhesion, low cost | Metal | $$ |
| Teflon Coating | Fluorinated polymer material/PTFE adheres and solidifies on the surface of the workpiece through a specific method. | CNC machining, Sheet metal fabrication，Die Casting | Non-stick surface for easy cleaning. Extremely low friction — ideal for oil-free bearings, gears, rails, and ski coatings. Excellent chemical, temperature, and weather resistance. UV & climate resistant | Metal, plastic, ceramic | $$$ |
| Electrophoretic | An advanced process combining electrochemistry and coating technology, paint particles “swim” to the workpiece surface and adhere uniformly under an electric field. | CNC machining, Sheet metal fabrication，Die Casting | No dead corners covers complex cavities, gaps, and edges. Uniform, precision-controlled coating with strong adhesion and excellent corrosion resistance. Highly automated & eco-friendly. | Metal | $$ |
| Passivation | Chemically or electrochemically converts the metal surface from active to inert (passive), significantly boosting its corrosion resistance. | CNC machining, Sheet metal fabrication，Die Casting | Improving wear resistance, passivation treatment hardly changes the size and color of the workpiece, and is non-conductive. | Metal | $$ |
| Alodine | Alodine is essentially a special chemical conversion coating treatment used for aluminum and aluminum alloys, belonging to a type of chromate treatment. | CNC machining, Sheet metal fabrication，Die Casting | Unparalleled adhesion, barrier & self-healing corrosion protection, extends aluminum corrosion resistance. Ultra-thin, conductive, dimensionally neutral. Decorative colors available. Enhances structural adhesive & sealant reliability | Metal | $$ |
| Chromate | Formation of passivation film for enhanced corrosion and oxidation resistance | CNC machining, Sheet metal fabrication，Die Casting | At a lower cost, it provides a surface solution that combines excellent corrosion resistance , enhanced adhesion, decorative color, and does not affect conductivity. | Metal | $$$ |
| PVD | PVD is like “evaporating” a material (such as titanium or chromium) in a vacuum, allowing its vapor to condense on the surface of the workpiece, forming a strong thin film. | CNC machining, Sheet metal fabrication，Die Casting | Gorgeous decoration: can be plated with TiN (gold), TiC (black), CrN (bright silver), etc. Extremely high hardness and wear resistance (such as DLC diamond-like coating). High temperature resistance, oxidation resistance, extremely thin coating, does not change the accuracy of the workpiece. | Metal, ceramic, plastic | $$$$ |
| CVD | The chemical reaction forms a thin film that improves abrasion resistance, high temperature resistance and corrosion resistance. | CNC machining, Sheet metal fabrication，Die Casting | Hard alloy, high-speed steel, ceramic | $$$$ | |
| DLC | DLC is a high-performance carbon based thin film formed by vapor deposition technology, which combines the high hardness of diamond and low friction properties of graphite. | CNC machining, Sheet metal fabrication，Die Casting | Ultra high hardness and ultra-low friction. | Metal | $$$$ |
| Electroless Plating | Homogeneous deposition of metallic coatings to improve corrosion resistance, abrasion resistance and electrical conductivity. | CNC machining, Sheet metal fabrication，Die Casting | Uniform coating on any complex shape. Precise thickness, no complex fixtures. Heat treatment to HV 1000 (near hard chromium). Corrosion resistant, weldable, magnetic/non-magnetic options. | Metal, plastic，silicone, glass | $$ |
| Electropolishing | Electrolysis removes minor surface imperfections and enhances smoothness and brilliance. | CNC machining, Sheet metal fabrication，Die Casting | Smooth, corrosion-resistant, hygienic. Reaches unreachable areas. No dimensional change. Medical/Food/Semiconductor grade. | Metal | $$ |
| Polishing | Rubbing or grinding surfaces to enhance smoothness and brilliance. | CNC machining, Sheet Metal Fabrication,Injection Molding,Die Casting 3D Printing, Vacuum Casting | Beautify appearance, high gloss, reduce surface defects and frictional resistance | Metals, plastics, ceramics | $$ |
| Mirror Polishing | Refers to the highest level of polishing where the surface is treated to have a mirror like optical reflection effect, which can clearly reflect the image. | CNC machining，Die Casting | Higher requirements than ordinary polishing, almost all for beautifying the appearance and decorating the surface. | Metals, plastics, ceramics | $$$$ |
| Shot Peening/Shot Blasting | Uses round media (steel, glass, ceramic balls) to improve fatigue strength & stress corrosion resistance, or for cleaning, rust/scale removal, deburring, and surface roughening. | CNC machining，Die Casting | Generates compressive stress to boost fatigue strength & stress corrosion resistance. Cleans surface (rust/scale removal) & creates a uniform matte finish. | Metals | $$ |
| Tumbling | Rotating or vibrating container creates rolling between workpiece and abrasive to remove burrs & sharp edges. Ideal for high-volume, small, non-deformable, impact-resistant parts. | CNC Machining, Sheet metal fabrication | Boosts surface hardness, removes oil/rust/impurities. Batch-deburrs sharp edges smoothly and safely at very low cost. | Metals, Plastics, Glass | $$ |
| Silk Screen | Ink is poured over a hollow-patterned screen, leaks through onto the workpiece, then dries or cures (baking/UV) to form the final pattern or text. | CNC machining, Sheet Metal Fabrication,Injection Molding,Die Casting 3D Printing, Vacuum Casting | Almost any material such as plastic, metal, glass, wood, and shape can be printed. | Metal, plastic,glass,etc | $ |
| Laser Engraving | The laser beam heats, melts or evaporates to mark, engrave or pattern engraving. | CNC machining, Sheet Metal Fabrication,Injection Molding,Die Casting 3D Printing, Vacuum Casting | A focused laser beam instantly vaporizes material for deep carving or alters its color/structure for marking, creating permanent marks. | Metal, plastic | $ |
| Knurling | Kuurling is a plastic processing technique that forms anti slip patterns on the surface of a rotating workpiece through extrusion or cutting. | CNC machining | Provide an anti slip grip surface to enhance the bonding strength of the mating parts and improve the industrial aesthetic and texture of the product. | Metals with good ductility, like aluminum, low-carbon steel, stainless steel, etc | $$ |
Typical Tolerances by EDM Process
Note: Values shown are typical industry ranges under stable production conditions. Actual tolerances depend on part geometry, material, and machining strategy. If 2D drawings aren’t available, we’ll apply ISO 2768 mk.
| Electrical Discharge Machining Tolerances | ||
| Feature | Standard Tolerance | Tightest Achievable |
| Linear Dimensions | ±0.01 mm (±0.0004″) | ±0.005 mm (±0.0002″) |
| Hole Diameter | ±0.015 mm (±0.0006″) | ±0.008 mm (±0.0003″) |
| Slot Width | ±0.02 mm (±0.0008″) | ±0.01 mm (±0.0004″) |
| Edge Radius / Corner | R0.2 mm typical | R0.1 mm possible |
| Surface Finish (Ra) | 1.2-3.2 µm | Down to 0.8 µm with polishing |
| Standards Applied | ISO 2768-m / ISO 2768-f | ISO 286, DIN ISO 1302 etc. |
| Wire EDM Tolerances（ slow-wire EDM High -precision) | ||
| Feature | Standard Tolerance | Tightest Achievable |
| Linear Dimensions | ±0.005 mm (±0.0002″) | ±0.002 mm (±0.00008″) |
| Hole Diameter | ±0.006 mm (±0.00024″) | ±0.0025 mm (±0.0001″) |
| Slot Width | ±0.008 mm (±0.0003″) | ±0.003 mm (±0.00012″) |
| Edge Radius / Corner | R0.05-0.1 mm typical | Down to R0.02 mm |
| Surface Finish (Ra) | 0.6-1.6 µm | As low as 0.2 µm (multi-pass) |
| Standards Applied | ISO 2768-f, GB/T 1804-2000 | ISO 1302 for surface finish |
| Wire EDM Tolerances（Medium-Speed EDM) | ||
| Feature | Standard Tolerance | Tightest Achievable |
| Linear Dimensions | ±0.01 mm (±0.0004″) | ±0.005 mm (±0.0002″) |
| Hole Diameter | ±0.012 mm (±0.0005″) | ±0.006 mm (±0.00024″) |
| Slot Width | ±0.015 mm (±0.0006″) | ±0.007 mm (±0.00028″) |
| Edge Radius / Corner | R0.1-0.2 mm | |
| Surface Finish (Ra) | 1.2-2.5 µm | ~1.0 µm with secondary pass |
| Standards Applied | Cost-effective fine cutting | Tooling, jigs, semi-precision |
| Wire EDM Tolerances（Fast-wire EDM) | ||
| Feature | Standard Tolerance | Tightest Achievable |
| Linear Dimensions | ±0.02 mm (±0.0008″) | ±0.01 mm (±0.0004″) |
| Hole Diameter | ±0.03 mm (±0.0012″) | ±0.015 mm (±0.0006″) |
| Slot Width | ±0.03 mm (±0.0012″) | ±0.015 mm (±0.0006″) |
| Edge Radius / Corner | R0.2-0.3 mm | / |
| Surface Finish (Ra) | 2.0-3.2 µm | / |
| Standards Applied | Fast prototyping, low-cost | General cutting, mold blanks |
Custom Parts For Different Industries
Provide CNC Machining One-Stop Services for Different Industries
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Which Process Should I Choose？ CNC vs. Other Manufacturing Methods
| Process/Method | Description | Best For | Key Benefits | Typical Lead Time |
| CNC Machining | Removes material from a solid block | High precision, tight tolerances, any quantity | MOQ 1 piece and fast delivery, no need mold | 3–10 working days |
| 3D Printing | Builds layer by layer | Complex internal structures, prototypes, low volume | MOQ 1 piece and fast delivery, no need mold | 1–3 working days |
| Injection Molding | Injects molten material into a mold | High-volume plastic parts | For mass production parts, cost-effective | 15–25 working days |
In summary: CNC machining is the go-to manufacturing process when you need high precision, tight tolerances, wide material selection, and reliable repeatability，from one-off prototypes to production runs of thousands of parts.
Would you like to start a project with us?
End-to-End 6D Solutions, From Concept to Mass Production. Integrated 5 Steps Quality Control Across Every Stage.
Phase 1:TR / PRD (Technical Review / Product Requirements Definition)
DFM, material selection & tolerance optimization for manufacturability. .
Concept Validation: Support rapid prototyping for functional verification; identify structural and process risks early.
Cost Engineering: Deliver cost-oriented feedback to minimize redesign cycles prior to EVT.
Phase 2: EVT (Engineering Verification Test)
Precision Engineering: One-stop solutions combining high-speed CNC machining and precision injection molding to deliver tight-tolerance parts for validation testing.
Engineering Support: Offer all-round engineering support including tolerance stacking analysis, surface treatment recommendations, and design optimization.
Phase 3: DVT (Design Verification Test)
Agile Revisions: Quick response to design modifications, ensuring rapid turnaround for the next round of prototype verification.
Visual Samples: Provide visible samples (appearance masters) for design approval.
Incoming Control: IQC (Incoming Quality Control) services to secure material quality.
Phase 4: MVT (Medium-Volume Verification Test)
Process & Fixture Validation: Verify the stability of the production process and the reliability of fixtures/tooling.
Full-Line QC: Implement IQC (Incoming Quality Control) , IPQC (In-Process Quality Control) , and OQC (Outgoing Quality Control) to monitor pilot run quality.
Phase 5: PVT (Process Verification Test)
BOM & Version Control: Identify trial production issues.
Process Standardization: Establish Golden Line production standards to ensure process repeatability and stability.
Comprehensive QC: Full suite of IQC (Incoming Quality Control) , IPQC (In-Process Quality Control) , and FQC (Final Quality Control) services.
Phase 6: MP (Mass Production)
ISO-Certified QC: Full documentation for guaranteed quality.
Lean Manufacturing: Optimize cost & quality.
Efficiency Boost: Modular fixtures for quick changeover.
Full-Lifecycle QC: Routine IQC/FQC/OQC + Post-sale CAPA for continuous improvement.
How can we work close with our client?
A – Z Assistance:
1)Our professional team will provide 24/7 Engineering Support
by one-on-one assistance.
2)Our experienced engineers will freely review and optimize your part designs (DFM), provide actionable feedback, and deliver competitive quotations, which all based on your design drawings, application requirements, and desired outcomes.
4)Throughout production, you’ll receive progress updates every 2–3 days.
5) Upon completion, we’ll share high-quality photos of finished parts and packaging, along with full documentation: inspection reports, shipping details, and material certifications.
CNC Machining with Expert DFM & Engineering Support
What Our Engineering & DFM Support Includes?
Design Review
Analyze CAD models for manufacturability, tolerance feasibility, and material suitability
Material Selection
Recommend the optimal metal, plastic, or composite based on strength, cost, and application needs。
Design Optimization
Adjust sharp corners, deep cavities, thin walls, or hard-to-machine details for efficient production
Tolerance Analysis
Ensure critical dimensions are achievable while avoiding unnecessarily tight tolerances that drive up cost
Tool Access Check
Identify features that may require special tooling or 5-axis machining
Cost Reduction Suggestions
Propose design changes that reduce cycle time, tool wear, or secondary operations
How to work with RPD?
Upload Design Drawing
- Send 2D/3D drawing online or by email
- Design Drawing format: STEP, IGES, DWG, PDF, STL, etc
- If you have multiple files, zip them or send by email to ashley@rdpmfg.com
DFM Analysis & Quote
- Our engineer team will review & analyze every file carefully.
- Request more details or provide optimize solution.
- Offer accurate quote with 6 hours.
Order Confirmation
- Confirm order & delivery details, sign the contract.
- Arrange & start to production.
- Check and confirm all details during production, Track every steps.
Parts Delivered
- Control quality during production.
- Provide order photos,inspection sheet and other request documents.
- Pack & label orders, then shipping.
FAQs About Our EDM or Wire EDM Services
Why CNC EDM or wire EDM?
Choose EDM when you need to machine very hard materials, create sharp internal corners, deep narrow slots, or delicate thin-walled parts with zero cutting force and no burrs, but be prepared for slow material removal and higher cost.
What kind of equipment do you use?
Our factory equip with advanced Sinker EDM machine, Wire EDM machine.
Do you offer surface finishing and assembly services after EDM?
Yes, exactly. We offer anodizing, sand blasting, plating, polishing, painting, and other surface treatments. Assembly of milled parts into sub-units is also available to streamline your production process.
What is your quality control system?
We operate under a rigorous Quality Management System (QMS) aligned with ISO standards. Our 5 Steps QC process is including IQC (Incoming Quality Control) , FQC (Final Quality Control) , OQC (Outgoing Quality Control) for routine production.
QE (Quality Engineering) / CAPA (Corrective and Preventive Actions) implemented throughout the entire product lifecycle, especially during the post-sale stage, to drive continuous improvement. Simply speaking 100% inspection before shipment to ensure zero defects.
What kind of quality assurance or warranty do you offer on orders?
One of the reasons engineers purchase from RPD is that we take on all the risks for you. We guarantee you’ll love what you get. Not happy with it? We’ll either redo it or give you a full refund. Your purchase is completely risk-free.
What's kind of material can you process of EDM service??
There are a wide range of metals: Hardened steel, carbide, HSS, titanium, Inconel.
Which kind of file formats can I send for EDM projects?
We accept STEP, IGES, STL, DWG, DXF, and other common CAD formats.
CNC Resources
What is a CNC Machining Center?
A CNC machining center is an advanced, computer-controlled machine tool capable of performing multiple machining operations—such as milling, drilling, tapping, boring, and sometimes turning.
Ashely . March 9, 2026
How many kinds of Types in CNC Machining Centers?
There are at least 5 different CNC lathes type in Machining Centers: Vertical Machining Center, Horizontal Machining, 5-Axis Machining Center, Gantry / Bridge Mill, Turn-Mill Center (Multi-Tasking).
Ashely . March 9, 2026
What is CNC Machining?
CNC (Computer Numerical Control) machining is a subtractive manufacturing process in which pre-programmed computer software controls the movement of factory tools and machinery to remove material from a solid workpiece, creating a finished part or product.
Ashely . March 9, 2026