MDR Series Solid Carbide Micro Thread Relief Grooving Bars for Small Bore Machining

Solid carbide MDR micro thread-relief grooving bars for machining internal thread runouts, relief grooves and narrow undercuts in small bores. Right-hand MDR and left-hand MDL versions are available, with standard, stainless-steel and custom configurations for precision turning applications.
Substrat:Fine-Grain Solid Carbide
Werkzeug-Typ:Micro Thread Relief Grooving Bar
Serie:MDR / MDL
Cutting Direction:Right-Hand / Left-Hand
Minimum Bore:Ø4.1 / Ø5.1 / Ø6.1 mm
Shank Diameter:Ø4 / Ø6 mm
Working Length:18 / 24 / 27 mm
Custom Options:Dimensions / Coolant Layout / Marking
Standard Dispatch1–3 Working Days
OEM & CustomDrawings / Samples
Minimum OrderMOQ 10 Pieces
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Consistent Quality

Consistent geometry across repeat orders.

Flexible Bestellungen

Small batches and mixed sizes available.

OEM Support

Custom marking, labels and packaging.

Standard und Sonderanfertigungen

Standard sizes and custom configurations.

MDR Micro Thread Relief Grooving Bars

MDR series solid carbide micro grooving bars are designed for machining thread-relief grooves, thread runout areas and internal undercuts in small bores. The precision-ground cutting geometry combines a narrow 1.5 mm cutting section, R0.5 corner radius and compact neck design for controlled access near internal threads and shoulders.

Available in right-hand MDR and left-hand MDL configurations, the series covers minimum bore diameters from 4.1 mm to 6.1 mm. Standard, stainless-steel and drawing-based customized versions are available for precision components, sleeves, bushings and Swiss-type CNC turned parts.

Produktübersicht

MDR solid carbide micro thread relief grooving bars

Key Product Advantages

Thread-Relief Geometry
Precision-ground profile for producing controlled relief and runout grooves next to internal threads.
Small-Bore Access
Standard models support minimum machining diameters of Ø4.1, Ø5.1 and Ø6.1 mm.
Solid Carbide Construction
Integral carbide construction provides rigidity and helps control deflection during precision small-bore machining.
Right- and Left-Hand Options
MDR right-hand and MDL left-hand tools support different spindle directions, holder positions and machining paths.

Typische Anwendungen

Anmeldung Machining Purpose
Internal Thread Relief Produces a controlled runout area at the end of an internal thread.
Internal Undercutting Machines narrow relief features behind internal shoulders and stepped bores.
Shoulder Relief Creates tool clearance and seating relief near an internal shoulder.
Chamfering & Profiling Supports light internal chamfering and profile finishing when permitted by the tool path and component geometry.

application material MIR micro boring bars

Product Detail Photo

MDR Series Solid Carbide Micro internal boring bar 3pcs MDR Series Solid Carbide Micro internal boring bar real photo MDR Series Solid Carbide Micro internal boring bar real photo back sideMDR micro thread relief grooving bar cutting edge detailMDR Series Solid Carbide Micro Thread Relief Grooving Bars for Small Bore Machining 1micro boring bars carbide internal tooling all sereis Micro internal tooling selection guide for boring, grooving, threading and profiling applications

Tool Geometry & Structure

MDR micro thread relief grooving bar tool structure

The MDR cutting profile combines a 45° front transition, 3° clearance geometry, R0.5 corner radius and a 1.5 mm cutting section. This geometry provides clearance for machining narrow relief features inside restricted bores.

For best stability, select the shortest working length that can reach the groove and verify the complete approach, cutting and retraction path before machining.

Tool Nomenclature & Selection Guide

Select the MDR or MDL micro thread-relief grooving bar according to cutting direction, minimum bore diameter, working length, corner radius, workpiece material and required internal clearance.

Code Beschreibung Example
MDR / MDL Cutting Direction MDR = Right Hand / MDL = Left Hand
4 / 5 / 6 Minimum Bore Size Group Minimum bore Ø4.1 / Ø5.1 / Ø6.1 mm
R0.5 Corner Radius 0.5 mm radius
L18 / L24 / L27 Working Length L1 18 / 24 / 27 mm
SSS Stainless Steel Version MDR 4 R0.5 L18 SSS

Dimensions & Available Sizes

MDR micro thread relief grooving bars dimension drawing and size chart

Dimensions are shown in millimetres. Custom sizes, left-hand tools and application-specific geometries are available according to drawings.

Standard Model Dimensions

Modell F L1 L H B1 B R Shank d Min. Bore
MDR 4 R0.5 L18 1.8 18.0 50 0.8 1.5 3.8 0.5 4.0 4.1
MDR 5 R0.5 L24 2.3 24.0 50 1.2 1.5 4.8 0.5 6.0 5.1
MDR 6 R0.5 L27 2.8 27.0 60 1.4 1.5 5.8 0.5 6.0 6.1

Model Selection by Minimum Bore

Minimum Bore Diameter Recommended Model Working Length
Ø4.1 mm or larger MDR 4 R0.5 L18 18 mm
Ø5.1 mm or larger MDR 5 R0.5 L24 24 mm
Ø6.1 mm or larger MDR 6 R0.5 L27 27 mm

Selection & Setup Guidance

Cutting Direction Use MDR for right-hand machining and MDL for left-hand machining.
Tool Reach Use the shortest working length that can safely reach the relief groove.
Tool Alignment Confirm center height, tool orientation, spindle direction and cutting path before machining.
Rostfreier Stahl Add the SSS suffix when ordering the stainless-steel application version.

Ordering Examples

Standard Right-Hand Tool: MDR 4 R0.5 L18

Stainless Steel Version: MDR 4 R0.5 L18 SSS

Left-Hand Version: Change MDR to MDL

Related Micro Internal Tooling Series

Internal Threading: MIR / MIL Series

Internal Grooving: MGR Series

Radius Grooving: MKR Series

Micro Boring: MTR Series

Micro Internal Tooling Catalog

View the complete micro boring, grooving, profiling and threading tool range in the HY Micro Internal Tooling Catalog (PDF).

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.

● Micro Boring Bars

MPR series and customized small-diameter boring tools for precision internal machining and anti-vibration applications.

● Micro Internal Threading Bars

MIR/MIL series with customized thread profiles, dimensions and product identification requirements.

● Micro Grooving Tools

Internal grooving and special groove solutions for miniature precision components.

● Custom Micro Tooling

Non-standard dimensions, special geometries and customer drawing-based tooling solutions are available.

mini boring bars

Customization Options

Custom laser marking for micro internal tooling

Laser Marking & Product Identification

Custom logo, model number and product identification marking can be provided according to distributor and brand requirements.

Custom packaging solution for micro tooling

Custom Packaging

Individual packaging, labels and product information can be customized to support reseller sales channels and private brand development.

Technical documentation support for tooling OEM

Technical Documents & Product Support

Support technical drawings, specifications and product information to help distributors promote and manage their tooling products.

OEM Workflow

01. Requirement Review

Confirm drawings, specifications, materials and packaging requirements.

02. Tool Confirmation

Finalize tool design, marking details and production requirements.

03. Sample Approval

Provide samples for testing and approval before batch production.

04. Batch Production

Produce and inspect according to confirmed requirements.

custom cutting tool process hy cutting tools

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

Quality control inspection for carbide cutting tools
01 Material Inspection

Verify carbide material quality and consistency before production.

02 Precision Grinding Control

Control tool geometry, dimensions and cutting edge accuracy during manufacturing.

03 Cutting Edge Inspection

Inspect edge quality and surface finish to maintain stable cutting performance.

04 Final Quality Inspection

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

Carbide cutting tool packing and 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

01

Auftragsbestätigung

02

Production Scheduling

03

Quality Inspection

04

Packing

05

Shipment

export packing way hy cutting toolsShipping and payment hy cutting tools end mill drills

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 MDR micro thread relief grooving bars used for?
MDR series tools are designed for machining thread-relief grooves, thread runout areas and narrow internal undercuts in small bores. They can also perform light chamfering and profiling when permitted by the component geometry and machining path.
What is the difference between MDR and MDL tools?
MDR identifies the right-hand version, while MDL identifies the left-hand version. Selection depends on the spindle direction, toolholder position, approach direction and required cutting path.
What minimum bore diameters are available?
The standard MDR range supports minimum bore diameters of Ø4.1 mm, Ø5.1 mm and Ø6.1 mm. The bore must also provide sufficient clearance for the complete cutting and retraction movement.
What is the standard cutting profile of the MDR series?
The standard tools use an R0.5 corner radius, a 1.5 mm cutting section and a geometry incorporating a 45° transition and 3° clearance. Custom profiles can be produced according to the required thread-relief or undercut feature.
Is there an MDR version for stainless steel machining?
Yes. Add the SSS suffix when ordering the stainless-steel application version. For example, MDR 4 R0.5 L18 SSS identifies the stainless-steel version of the standard right-hand model.

Selection & Application FAQs

How do I select the correct MDR model?
Select the tool according to minimum bore diameter, required working length, cutting direction, groove profile, workpiece material and available tool clearance. Use the shortest model that can safely reach the machining position.
Does the 4, 5 or 6 in the model number indicate shank diameter?
Not in every model. The numbers 4, 5 and 6 identify the minimum bore size group. MDR 4 has a Ø4 mm shank, while both MDR 5 and MDR 6 use a Ø6 mm shank. Always confirm the shank dimension shown in the size chart.
Which MDR model should I use for my bore diameter?
Use MDR 4 R0.5 L18 for bores of Ø4.1 mm or larger, MDR 5 R0.5 L24 for bores of Ø5.1 mm or larger, and MDR 6 R0.5 L27 for bores of Ø6.1 mm or larger. Additional clearance may be required depending on the groove position and tool path.
How can I improve machining stability with an MDR tool?
Use the shortest possible working length, minimize tool overhang, confirm center height and cutting direction, and use a rigid precision holder. Cutting speed and feed should be adjusted according to the workpiece material, groove depth and machine rigidity.
How should I check tool clearance before machining?
Check the bore diameter, groove position, shoulder clearance and complete approach and retraction path. A component drawing is recommended when the relief groove is deep inside the bore or positioned close to an internal shoulder.

Ordering & OEM FAQs

Can you manufacture custom MDR or MDL grooving bars?
Yes. The corner radius, relief width, relief depth, cutting profile, working length, minimum bore diameter, shank diameter, cutting direction and coating can be customized according to drawings or samples.
What information is required for an MDR quotation?
Please provide the standard model or component drawing, minimum bore diameter, relief-groove dimensions, machining depth, tool direction, workpiece material, required quantity and any coating, marking or packaging requirements.
Can I order mixed models or small quantities?
Yes. The standard minimum order quantity is 10 pieces. Mixed-model orders and sample quantities can be reviewed according to the selected specifications and available stock.
Is OEM marking and private-label packaging available?
Yes. Custom laser marking, model identification, labels and private-label packaging are available for distributors, tooling suppliers and industrial customers.
What is the lead time for standard and customized MDR tools?
In-stock standard models can usually be dispatched within 1–3 working days after order confirmation. Customized tools require separate lead-time confirmation according to geometry, coating, quantity and drawing approval.

Technische Ressourcen

Micro Internal Tooling Catalog HY Micro Internal Tooling Catalog (PDF)

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.

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Drawings, size lists and reference photos are welcome.

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