MTR Series Solid Carbide Micro Boring Bars for Small Bore Internal Turning
Consistent Quality
Consistent geometry across repeat orders.
Flexible Orders
Small batches and mixed sizes available.
OEM Support
Custom marking, labels and packaging.
Standard & Custom
Standard sizes and custom configurations.
MTR Solid Carbide Micro Boring Bar Overview
The MTR Series is a precision-ground solid carbide micro boring bar designed for internal turning, bore finishing and diameter correction in small-diameter holes. Its compact cutting geometry provides access to miniature bores and internal shoulders while the one-piece carbide construction helps maintain rigidity and dimensional stability.
Standard models cover cutting diameters from Ø0.8 to Ø11.9 mm, nose radii from R0.05 to R0.40 mm and clearance lengths from 3 to 50 mm. Standard and extended-length versions are available for precision components, sleeves, bushings, hydraulic parts and other CNC-turned components.
Key Product Features
Typical Applications
| Application | Machining Purpose |
|---|---|
| Small-Hole Boring | Enlarging and correcting small pre-machined holes to the required internal diameter. |
| Precision Bore Finishing | Final internal turning passes requiring controlled diameter, roundness and surface finish. |
| Internal Shoulder Machining | Finishing short internal steps, shoulders and recessed bore features. |
| Deep or Recessed Bores | Long-reach models provide access to internal features positioned farther from the bore entrance. |
Micro Internal Machining Methods
Recommended Workpiece Materials
Machine Compatibility
Precision internal turning and bore finishing.
Miniature and high-volume precision components.
Stable repetitive machining of small internal diameters.
Prototype, repair and small-batch internal turning.
Product Detail Photos
Product Video
Micro Internal Tooling Selection
Selection Recommendation
Select the MTR model according to cutting diameter d1, nose radius R, required cutting depth Q, clearance length L1, shank diameter D and overall length L. Use the shortest practical clearance length and the largest shank diameter permitted by the bore to maximize rigidity. Extended-length models should only be selected when the internal feature cannot be reached with a standard-length tool.
MTR Series Specifications
The MTR Series includes standard and extended-length solid carbide micro boring bars for small-bore internal turning. All dimensions shown below are in millimeters unless otherwise specified.
Model Designation
| Code | Meaning | Example Value |
|---|---|---|
| MTR | Tool series | Solid carbide micro boring bar |
| 39 | Cutting diameter d1 | Ø3.9 mm |
| R020 | Nose radius R | R0.20 mm |
| L200 | Clearance length L1 | 20 mm |
| 475 | Shank diameter D and overall length L | Ø4 mm shank, 75 mm overall length |
Model coding may vary for special or customized tools. Confirm all dimensions on the quotation or production drawing before ordering.
Dimension Definitions
| Symbol | Dimension | Description |
|---|---|---|
| d1 | Cutting Diameter | Diameter represented by the cutting edge and used to identify the model size. |
| R | Nose Radius | Cutting-edge radius affecting edge strength, cutting forces and surface finish. |
| Q | Cutting Depth | Catalog cutting-depth dimension for the specified tool geometry. |
| L1 | Clearance Length | Reduced-neck length available for entering the bore and reaching the machining position. |
| D | Shank Diameter | Nominal cylindrical shank diameter used for toolholding. |
| L | Overall Length | Total length of the boring bar from cutting edge to shank end. |
Small-Diameter Models: Ø0.8–Ø3.9 mm
Medium-Diameter and Long-Reach Models: Ø3.9–Ø5.9 mm
Large-Diameter and Extended-Length Models: Ø5.9–Ø11.9 mm
Standard Model Range
| Model Range | d1 | R | Q | L1 | D | L |
|---|---|---|---|---|---|---|
| MTR0.9–MTR1.8 | 0.8–1.7 | 0.05 / 0.10 | 0.10–0.20 | 3–7 | 4 | 50 |
| MTR2.0–MTR2.5 | 1.9–2.4 | 0.05 / 0.10 | 0.25–0.35 | 8–10 | 4 | 50 |
| MTR3.0–MTR3.5 | 2.8–3.4 | 0.05–0.20 | 0.35 | 8–22 | 4 | 50 |
| MTR4.0 | 3.9 | 0.05–0.40 | 0.45 | 10–25 | 4 | 50 / 75 / 100 |
| MTR4.5–MTR4.6 | 4.4–4.5 | 0.20 | 0.50 | 15–22 | 5 | 50 |
| MTR5.0 | 4.9 | 0.05–0.40 | 0.55 | 15–30 | 5 | 50 / 60 / 75 / 100 |
| MTR5.5–MTR6.0 | 5.4–5.9 | 0.05–0.40 | 0.65 | 15–30 | 6 | 50 / 60 / 75 / 100 |
| MTR7.0–MTR8.0 | 6.9–7.9 | 0.10 / 0.20 | 0.75–0.85 | 22–30 | 8 | 60 / 100 |
| MTR10–MTR12 | 9.9–11.9 | 0.20 | 1.05–1.25 | 35–50 | 10 / 12 | 75 / 100 |
The table provides a grouped range summary. Refer to the dimension charts above for the exact dimensions and availability of each model.
Extended-Length Options
Selection Guidance
Recommended Starting Conditions
- Set the cutting edge accurately on the spindle centerline.
- Use the shortest practical tool overhang and a high-precision holder.
- Check tool runout before machining miniature bores.
- Begin with a conservative depth of cut and feed, especially on long-reach models.
- Provide effective coolant or air flow to evacuate chips from the bore.
- Reduce cutting load if chatter, taper or dimensional variation occurs.
- Adjust speed and feed according to workpiece material, coating, rigidity and bore depth.
Related Micro Internal Tool Series
Profiling & Boring: MPR Series
Complex Internal Profiling: MQR Series
Grooving & Boring: MNR Series
Internal Grooving: MGR Series
We support distributors, tooling suppliers and industrial partners with flexible OEM and private label solutions for micro internal tooling products. From laser marking and customized packaging to product identification and technical documentation, we help customers build their own tooling product lines with reliable manufacturing support.
OEM Product Scope
We provide OEM and private label manufacturing solutions for micro internal tooling products, supporting distributors and tooling suppliers with standard series, customized specifications and drawing-based production.
MPR series and customized small-diameter boring tools for precision internal machining and anti-vibration applications.
MIR/MIL series with customized thread profiles, dimensions and product identification requirements.
Internal grooving and special groove solutions for miniature precision components.
Non-standard dimensions, special geometries and customer drawing-based tooling solutions are available.
Customization Options
Laser Marking & Product Identification
Custom logo, model number and product identification marking can be provided according to distributor and brand requirements.
Custom Packaging
Individual packaging, labels and product information can be customized to support reseller sales channels and private brand development.
Technical Documents & Product Support
Support technical drawings, specifications and product information to help distributors promote and manage their tooling products.
OEM Workflow
Confirm drawings, specifications, materials and packaging requirements.
Finalize tool design, marking details and production requirements.
Provide samples for testing and approval before batch production.
Produce and inspect according to confirmed requirements.
Private Label Support for Distributors
For distributors and tooling resellers, we provide flexible private label support including customized marking, packaging solutions and product documentation to help establish a professional tooling product range.
We follow strict quality control procedures from raw material inspection to final shipment. Each tool is inspected to ensure consistent dimensions, cutting performance and reliable quality for industrial machining applications.
Quality Control Process
Verify carbide material quality and consistency before production.
Control tool geometry, dimensions and cutting edge accuracy during manufacturing.
Inspect edge quality and surface finish to maintain stable cutting performance.
Confirm product specifications before packing and shipment.
Inspection Standards
| Inspection Item | Purpose |
|---|---|
| Material Inspection | Verify carbide quality and material consistency. |
| Dimension Inspection | Confirm tool size and tolerance requirements. |
| Cutting Edge Inspection | Check edge geometry and surface quality. |
| Final Inspection | Ensure products meet confirmed specifications before delivery. |
Packing & Protection
Individual protection and export packaging help prevent tool damage during storage and international transportation.
- Individual tool protection
- Product identification labels
- Batch traceability support
- Export shipment protection
Production & Delivery Workflow
Order Confirmation
Production Scheduling
Quality Inspection
Packing
Shipment
Delivery Support
Standard products can usually be shipped within 1–3 working days after order confirmation. Customized products require confirmation according to tool design, quantity and production requirements.
FAQ & Downloads
Product FAQs
What are MTR micro boring bars used for?
What cutting diameters are available in the MTR Series?
Which nose radii are available?
Are long-reach MTR boring bars available?
Selection & Application FAQs
How do I select the correct MTR boring bar?
Which workpiece materials can be machined?
How can I reduce vibration when boring a small hole?
How should chips be removed from a small bore?
Can the MTR bar machine hardened steel?
Ordering & OEM FAQs
Can you manufacture custom MTR micro boring bars?
Can distributors order mixed MTR models?
Is private-label packaging and OEM marking available?
What information is required for a quotation?
What is the lead time for MTR boring bars?
Technical Resources
Need Sizes, Pricing or Custom Options?
Send us the required tool type, sizes, quantities, workpiece material and any OEM or custom requirements. We will confirm suitable specifications, availability, lead time and quotation details.
Drawings, size lists and reference photos are welcome.
