Precision Mold
Cores & Cavities
Machined to Fit
High-accuracy cores and cavities for injection molds, built from P20, H13, S136, and NAK80. Tight contour tolerances, controlled fit, and full CMM reporting.
×400mm
VDI 12-45
What Are Mold Cores & Cavities?
The two fundamental components that define every molded part's geometry, dimensions, and surface quality.
Core (凸模)
The male component that forms the interior geometry of the molded part. Cores define internal features such as bosses, ribs, holes, and undercuts. They must withstand high injection pressures and repeated thermal cycling.
Cavity (型腔)
The female component that forms the exterior geometry of the molded part. Cavities define the visible surfaces, cosmetic finish, and outer dimensions. Surface quality directly impacts part appearance and dimensional accuracy.
Why Both Must Be Machined Together
The parting line fit, contour match, and dimensional stack-up between core and cavity directly determine the molded part's wall thickness, flash risk, and dimensional conformance. At YCS, we machine mating pairs from the same setup references to guarantee controlled fit.
What We Machine -- And What to Discuss First
We Routinely Machine
- Injection mold cores, cavities, and inserts
- High-gloss cosmetic surface molds (SPI A1-A2)
- Deep-cavity structures with high ribs and thin walls
- Interchangeable cores/cavities for multi-cavity molds
- Hot runner system compatible components
- Mold components to HASCO, DME, LKM, FUTABA standards
- Replacement and spare cores/cavities for existing molds
Discuss with Our Engineers First
- Projects without complete 3D/2D drawings -- we need full geometry data to quote accurately
- Oversized components exceeding machine travel -- confirm dimensions upfront
- Exotic or non-standard materials -- availability and lead time must be verified
- Extremely thin walls below 0.3mm -- feasibility depends on material and geometry
- Very deep cavities with aspect ratio above 10:1 -- tooling access must be evaluated
Not sure if your project is in scope? Send us your drawing or a brief description -- our engineers will assess feasibility within 24 hours at no charge.
Material Selection & Hardness Guide
Choosing the right steel grade determines mold life, surface quality, and total cost of ownership. We supply material test reports (MTR) with every order.
| Material | Hardness (HRC) | Best For | Evidence Provided |
|---|---|---|---|
| P20 | 28-32 HRC | Medium-to-low volume production, general cosmetic parts, prototype tooling |
MTR
Hardness report
|
| 718H | 33-37 HRC | High-polish requirements, medium production volumes, consumer goods |
MTR
Hardness report
Polish test
|
| NAK80 | 37-43 HRC | Mirror-finish requirements, transparent parts, optical components |
MTR
Hardness report
Ra measurement
|
| H13 | 48-52 HRC | High wear, hot runner systems, glass-fiber reinforced materials, die casting |
MTR
HT report
Hardness cert
|
| S136 | 48-52 HRC | Corrosive environments, medical-grade, food-contact, PVC, flame retardant resins |
MTR
HT report
Corrosion test
|
Material Test Report (MTR)
Full chemical composition and mechanical property certification from mill source, provided with every order.
Hardness Verification
Incoming and post-heat-treatment Rockwell hardness testing documented and included in the inspection package.
Heat Treatment Records
Time-temperature charts and furnace certification for all heat-treated components, traceable to part serial number.
Maximum Size & Geometric Capabilities
Equipment Highlights
In-house machinery -- no subcontracting for core operations
Tolerance, Fit & Surface Finish Standards
Profile Tolerance
±0.005 mmContour accuracy for complex 3D surfaces, verified by CMM full-surface scan.
Position Tolerance
±0.003 mmBore, pin, and feature position relative to datum, critical for multi-cavity interchangeability.
Concentricity
±0.004 mmCoaxial features for rotating inserts, sprue bushings, and cylindrical cores.
Fit Tolerance
H6/g5 to H7/f7Controlled mating fits between core/cavity and mold base for proper seating and no flash.
Mirror Polish
Ra ≤ 0.025 μmSPI A1/A2 optical-grade finish for transparent parts and high-gloss cosmetic surfaces.
EDM Texture
VDI 12-45Spark-eroded texture finishes for grip surfaces, hiding sink marks, and technical aesthetics.
Complex Geometry We Handle In-House
Deep Cavity Machining
Depth-to-width ratios up to 8:1 standard, 10:1 on engineering review. We use extended-reach tooling, high-pressure coolant, and optimized chip evacuation strategies to maintain accuracy at depth.
High Rib & Thin Wall Structures
Minimum wall thickness from 0.5 mm in steel (material-dependent). We control cutting forces, fixture rigidity, and tool path sequencing to prevent deflection and maintain dimensional stability.
Complex 3D Freeform Surfaces
5-axis simultaneous machining for organic shapes, compound curves, and non-prismatic geometries. EDM electrode design and spark erosion for features unreachable by cutting tools.
Threads, Undercuts & Mating Faces
Internal and external thread cores, side-action mating surfaces, and lifter interface geometry. We machine parting line and shut-off faces to controlled flatness and angular tolerances for leak-free mold seating.
From Raw Material to Delivery-Ready Component
Every core and cavity follows a documented manufacturing route with inspection gates at each critical transition point.
Material Selection & MTR Review
Steel grade confirmed against application requirements. Mill test report reviewed for chemistry, hardness, and cleanliness. Material lot number recorded for full traceability.
Rough Machining
Bulk material removal to leave 0.3-0.5 mm stock on critical surfaces. Datum features established for all subsequent operations. Stress relief if required by material spec.
Heat Treatment
Vacuum hardening or nitriding per material and hardness specification. Time-temperature records archived. Post-HT hardness verified by Rockwell tester.
Precision CNC / 5-Axis Machining
Semi-finish and finish passes on hardened steel. 5-axis simultaneous for complex contours. Tool path verified against 3D model. In-process probing at critical features.
EDM Finishing
Sinker EDM for sharp corners, deep slots, and features unreachable by cutting tools. Wire EDM for precise contour cuts and thin ribs. Electrode design and spark gap compensation documented.
Grinding & Polishing
Surface and profile grinding for flat and cylindrical features. Manual and machine polishing to specified SPI or VDI finish. Roughness measurement with profilometer.
Waterline Drilling & Pressure Testing
Cooling channels drilled and interconnected per design. Pressure test at 10 bar minimum. Leak-free certification before final inspection.
Final CMM Inspection
Full-dimensional report on Zeiss CMM. All critical features measured against nominal 3D model. Report issued and archived with part serial number.
Protective Packaging & Delivery
Rust-preventive coating applied. Components wrapped and crated for international shipping. Inspection report, MTR, and HT records packed with each shipment.
Cooling Waterline Design & Verification
Effective cooling is not an afterthought -- it determines cycle time, part warpage, and dimensional consistency. We design and drill cooling circuits as an integral part of core and cavity manufacturing.
Conventional Waterlines
Straight-drilled channels with baffles and bubblers. Optimized circuit routing to maximize heat transfer while maintaining structural integrity of the component.
Spiral & Cascade Circuits
Helical waterlines around cylindrical cores and spiral circuits in cavity blocks for uniform temperature distribution and reduced hot spots near gate areas.
Conformal Cooling Design
Cooling channels that follow the contour of the mold surface for consistent wall-to-channel distance. Collaborative design with customer mold engineers using Moldflow thermal analysis.
Three-Stage Quality Control with Full Documentation
Incoming Inspection
Every material lot verified before machining begins.
- Mill Test Report (MTR) review
- Incoming hardness check (Rockwell)
- Dimensional verification of raw stock
- Material identification marking
- Lot number recorded in job traveler
In-Process Inspection
Critical dimensions checked at each manufacturing stage.
- First-article check after rough machining
- CMM sampling at semi-finish stage
- In-process probing on CNC machine
- EDM electrode dimension verification
- Surface roughness check after polishing
Final Outgoing Inspection
Full CMM report before every shipment -- no exceptions.
- Full-dimensional CMM report (all critical features)
- Surface finish measurement (profilometer)
- Hardness re-verification after heat treatment
- Visual inspection for surface defects
- Waterline pressure test certification
Inspection Equipment
Interchangeability Control & Part Traceability
For multi-cavity molds, every cavity and core must be interchangeable. We build and verify this systematically, not by chance.
Interchangeability Verification
All cavities in a multi-cavity set are machined from the same program, same setup references, and measured on the same CMM fixture. Dimensional variation between cavities documented.
Serial Number & Version Control
Every component receives a unique engraved serial number. Drawing revision, material lot, and inspection report are linked to the serial number in our job management system.
Reverse Engineering & Copy Parts
We can reproduce worn or damaged cores from physical samples using CMM scanning and CAD reconstruction. Replacement parts are verified to match the original within specified tolerances.
Spare Parts Management
We maintain original machining data, inspection records, and material specifications for reorder. Replacement parts can be produced to match the original without re-engineering.
Real Projects, Verified Results
Representative projects shown with customer-identifying details removed per NDA. Actual CMM reports and process data available on request.
H13 Deep-Cavity Core Set
8-cavity hot runner mold for glass-fiber reinforced PA66 connector housing. Deep cavity with 6:1 aspect ratio, conformal cooling, and parting line flatness requirement of ±0.003 mm.
S136 Mirror-Finish Cavity Pair
4-cavity mold for transparent polycarbonate lens housing. Mirror finish SPI A1 required on optical surfaces. Tight dimensional stack-up between paired cavities for uniform wall thickness.
NAK80 Multi-Insert Cavity Block
Interchangeable insert set for medical syringe barrel mold. 16 cavity inserts required to be dimensionally interchangeable within ±0.005 mm. Full CMM report and material traceability per FDA supplier requirements.
Frequently Asked Questions
What 2D/3D file formats do you accept?
We accept STEP (.stp, .step), IGES (.igs, .iges), SolidWorks (.sldprt, .sldasm), and Parasolid (.x_t) for 3D models. For 2D drawings, we accept DWG, DXF, and PDF. STEP is preferred for quoting as it provides the most complete geometric data. If you have a native CAD file from any major platform, please send it -- we can usually open or convert it.
What is the typical lead time for cores and cavities?
Lead time depends on complexity, material, and heat treatment requirements. Simple inserts without heat treatment: 7-12 working days. Standard cores/cavities with heat treatment: 15-22 working days. Complex deep-cavity or mirror-finish components: 22-30 working days. We provide a confirmed schedule with your quotation. Rush processing is available for urgent projects -- discuss with our team.
Can you match existing cores for replacement?
Yes. We regularly produce replacement cores from worn or damaged originals. If you have the original drawing and revision, we machine directly to print. If drawings are unavailable, we can CMM-scan the original part and reconstruct a 3D model for your approval before machining. Replacement parts are verified to match the original within the specified tolerance.
How do you ensure interchangeability in multi-cavity molds?
All cavities in a set are machined from the same CNC program, fixtured on the same datum references, and inspected on the same CMM setup. We measure the dimensional variation between cavities and document it in the inspection report. Cavities that fall outside the interchangeability tolerance are reworked before shipment. We do not ship a set unless all pieces pass the interchangeability check.
Do you provide CMM reports with every delivery?
Yes, always. Every shipment includes a full-dimensional CMM report covering all critical features specified on the drawing. The report is issued on our letterhead with the part serial number, drawing revision, material lot number, and inspection date. We use a Zeiss CMM with ±0.001 mm accuracy. Sample CMM reports are available on request before you place an order.
What surface finishes can you achieve?
We can achieve the full SPI range from A1 (mirror, Ra ≤ 0.025 μm) through D3 (rough sandblast). We also work to VDI 12 through VDI 45 for EDM texture specifications. For optical and medical applications, we offer electropolishing in addition to mechanical polishing. The achievable finish depends on the steel grade -- NAK80 and S136 are best for high-gloss requirements.
Do you sign NDAs?
Yes, we sign NDAs before receiving any customer drawings or technical data. We use a standard mutual NDA that covers drawing confidentiality, design data protection, and restrictions on use of your information. If you have your own NDA template, we are generally able to work with it after legal review. Protecting customer IP is standard practice at YCS -- we do not share customer data or use designs for any purpose other than fulfilling your order.
Explore Related Capabilities
Precision Mold Components
Full range of precision mold components machined in-house.
Mold Inserts
Interchangeable inserts for complex and multi-cavity molds.
Slides, Lifters & Parts
Side actions, lifters, and replacement tooling components.
CNC Mold Machining
High-precision CNC machining for mold bases and components.
EDM & Wire EDM
Sinker and wire EDM for hardened steel and complex geometry.
Quality Control
ISO 9001 quality system with CMM inspection and full documentation.
Request a Quote
Upload drawings and get a response from our engineers within 24 hours.
Request a Quote for
Mold Cores & Cavities
Upload your 2D/3D drawings, material requirements, and surface finish needs. Our tooling engineers will review and respond within 24-48 hours.