CNMG 120404/120408 R/L-S Carbide Turning Inserts for Steel Machining
CNMG 120404 and 120408 R/L-S carbide turning inserts are designed for stable external turning, facing and profiling of steel. The 80° diamond shape and double-sided negative geometry provide strong cutting edges, while right- and left-hand chipbreaker options support different feed directions, toolholders and machining requirements.
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.
◆Product Overview
The CNMG 120404/120408 R/L-S carbide turning inserts combine an 80° rhombic, negative-clearance insert body with a handed R or L cutting configuration. Specify them for external turning and facing of appropriate carbon and alloy steels with a compatible CNMG 1204 holder.
Choose the 0.4 mm nose radius for a smaller corner and lighter feeds, or 0.8 mm for greater corner support where the workpiece profile and machine rigidity allow. Select the actual carbide grade, coating and S-geometry for the material, chip control, cutting load and surface-finish target.
The R/L-S suffix must be checked against the offered manufacturer’s drawing and the holder setup. The standard CNMG geometry identifies a turning insert; a dedicated grooving operation requires a tool and cutting geometry qualified for the groove width and depth.
Quick Procurement Summary
| Insert Family | CNMG 1204; 80° rhombic | Tool Material | Cemented carbide |
|---|---|---|---|
| Listed Sizes | 120404 / 120408 | Nose Radius | 0.4 / 0.8 mm |
| Primary Material | Steel, ISO P; grade dependent | Operation | External turning / facing |
| Nominal Body | IC 12.70 mm; thickness 4.76 mm | Confirm Before Order | R/L-S geometry, grade, coating, holder fit |
Size references describe standard CNMG 1204 geometry. Availability, cutting edge, hole form, grade and coating must be confirmed for the complete item code.
Key Configuration Points
A standard negative-clearance CNMG body for a matching turning-tool pocket and clamp.
Confirm the handed cutting edge and S-style chip-control geometry against the supplier drawing.
Choose the radius alongside the feed, required profile clearance and rigidity of the setup.
Specify the substrate and coating for the actual steel grade, hardness and cut continuity.
◆Product Images
Application & Ordering Check
For a suitable configuration, provide the complete R/L-S code, holder model, steel grade and hardness, cutting direction, continuous or interrupted cut, coolant and order quantity.
See our CNC Insert Selection Guide, or request a grade and size quotation.
◆Specifications & Size Chart
The CNMG 1204 body has nominal inscribed circle (IC) 12.70 mm, thickness (S) 4.76 mm and fixing hole (D1) approximately 5.16 mm in published manufacturer catalogues. The 04 and 08 radius codes represent 0.4 and 0.8 mm respectively. The following four R/L-S combinations are selection references; confirm which are supplied in the requested grade.
| Model Reference | R/L-S Variant | IC* | Thickness S* | Hole D1* | Nose Radius |
|---|---|---|---|---|---|
| CNMG 120404R-S | R-S | 12.70 mm | 4.76 mm | ≈5.16 mm | 0.4 mm |
| CNMG 120404L-S | L-S | 12.70 mm | 4.76 mm | ≈5.16 mm | 0.4 mm |
| CNMG 120408R-S | R-S | 12.70 mm | 4.76 mm | ≈5.16 mm | 0.8 mm |
| CNMG 120408L-S | L-S | 12.70 mm | 4.76 mm | ≈5.16 mm | 0.8 mm |
◆Material & Configuration
| Specification | Selection Detail |
|---|---|
| Insert geometry | 80° rhombic CNMG body; negative 0° clearance, with a central fixing hole. |
| Substrate | Cemented carbide; obtain the exact supplier grade for the ordered code. |
| Main workpiece | Steel (ISO P); confirm carbon/alloy steel grade, hardness and cut continuity. |
| Cutting operation | External turning and facing; roughing range depends on the actual grade and chipbreaker. Not a dedicated deep-grooving insert. |
| R/L-S suffix | Handed variant and supplier-defined S geometry. Match the exact drawing, holder, cutting edge and feed direction. |
| Coating | PVD or CVD may be offered by grade; confirm coating designation and availability for each full code. |
◆How to Select the Insert
◆Starting Cutting Data
Use the grade- and geometry-specific cutting data supplied with the complete CNMG R/L-S model. The previous page's speed, feed and depth ranges span unrelated workpiece groups and do not establish settings for this steel product. Confirm steel grade/hardness, coolant, interrupted cutting and toolholder stability before a trial cut.
◆Related Guide & Ordering
For shape, nose-radius and chipbreaker selection, read our CNC Insert Selection Guide. Send the full model and holder code to confirm the R/L-S drawing, carbide grade, coating, stock and cutting data.
◆Carbide Insert Customization & OEM
Specify the insert around the machining operation, workpiece and holder. We can review standard replacements, application-specific geometry and private-label requirements using your insert designation, drawing or sample. Available grades, coatings, dimensions and order quantities are confirmed for each requested series.
Geometry & Chip Control
Review chipbreaker, rake, cutting-edge preparation, nose radius and corner design for the operation and workpiece. Confirm holder compatibility before approving a modified geometry.
Substrate & Coating
Select an available carbide grade and coating for the workpiece material, cutting conditions and desired balance of wear resistance and edge toughness.
Dimensions & OEM
Review insert size, thickness, locating and clamping features, tolerances, laser marking and private-label packaging against the approved specification.
◆Customization Options
Use the fields below when sending an inquiry. The exact options depend on the insert family and are confirmed in the quotation or approved drawing.
| Specification | Details to Confirm |
|---|---|
| Insert Type | Turning, milling, threading, grooving or drilling insert; send the designation or drawing. |
| Size & Fit | Shape, size, thickness, inscribed circle or edge length, hole or clamping form, and holder model. |
| Cutting Geometry | Chipbreaker, nose or corner radius, edge preparation, cutting direction and application-specific profile. |
| Grade & Coating | Workpiece group and grade, carbide substrate, coating system and wet or dry cutting conditions. |
| Tolerance & Inspection | Critical dimensions, profile requirements, inspection method and any required report. |
| OEM Presentation | Insert or box marking, label content, packaging format and quantity per pack. |
◆How to Request a Custom Insert
Send your insert requirements through our contact form or review our OEM and private-label service.
◆Carbide Insert Quality Control
Insert quality depends on the approved grade, geometry, coating and dimensional specification. We review the requirements at order confirmation and align the inspection scope with the insert series and any customer drawing. Share critical dimensions or documentation needs before production so they can be included in the agreed inspection plan.
01 · Incoming Material
Confirm the specified carbide grade or material documentation against the order requirements.
02 · In-Process Checks
Review dimensions and cutting-edge features during production against the approved specification.
03 · Final Inspection
Check the agreed dimensions, appearance, edge condition, coating identification and marking as applicable.
04 · Packing Review
Verify the item code, quantity, labels and protective packing against the approved order.
◆Inspection & Documentation
Inspection points and acceptance criteria should be agreed for the ordered series. For custom inserts, the approved drawing takes priority over a generic catalogue description.
| Check Area | What to Confirm |
|---|---|
| Dimensions & Fit | Insert size, thickness, corner radius, clamping features and any drawing tolerances. |
| Cutting Geometry | Chipbreaker, edge preparation, usable corners and profile where applicable. |
| Grade & Coating | Approved grade and coating designation; any requested verification method. |
| Appearance & Packing | Visible edge damage, marking, item code, count and packing format. |
| Requested Records | Inspection report, material or coating documentation, sample approval or batch identification when agreed. |
◆Order & Delivery
Share a line-by-line list of insert codes and quantities for a mixed-size quotation. Stock status, minimum quantity, sample requirements and production lead time are confirmed for each grade, coating and configuration.
Send your item list and quality requirements through our contact form for specification, availability and delivery confirmation.
◆Product FAQs
What is the difference between CNMG 120404 and 120408?
Both are CNMG 1204 bodies with the same nominal 4.76 mm thickness. The final digits indicate the nose radius: 120404 has 0.4 mm, and 120408 has 0.8 mm. Choose according to feed, profile clearance, finish and setup stability.
What do R/L-S indicate?
R and L distinguish handed versions of the offered cutting geometry, while S is part of the supplier's geometry or chipbreaker designation. Confirm the complete manufacturer's drawing, active edge, holder model and cutting direction; the suffix alone does not prove interchangeability between brands.
Are these CNMG inserts suitable for grooving?
This range is specified for turning and facing. A dedicated groove needs a tool matched to its groove width, depth and chip evacuation. Do not infer deep-grooving suitability from the R/L-S suffix or from the previous product description.
Will a CNMG 1204 insert fit any CNMG 1204 toolholder?
Check the pocket, clamp, fixing-hole form and approach angle, then verify that the selected R/L-S edge is exposed in the intended feed direction. Matching nominal size is only the first fit check.
Which carbide grade and coating should I use for steel?
State the exact steel grade and hardness, continuous or interrupted cut, coolant use, feed, depth of cut and wear problem. Select a grade and available PVD or CVD coating qualified for those conditions; neither coating type is guaranteed for every full model code.
What cutting speed, feed and depth should I start with?
Request the cutting-data range for the actual grade, chipbreaker and steel grade. The size code alone cannot establish these values. Begin within the supplier's applicable range and check chip formation, flank wear, edge chipping and finish in a trial cut.
◆Ordering & OEM FAQs
Which information is needed for a quotation?
Send each complete CNMG 120404/120408 R/L-S designation, holder code, steel grade, selected carbide grade and coating if known, quantity and destination. Supply a reference insert or drawing for replacement requests.
Are all four R/L-S variants available?
The four size and hand combinations are shown for selection. Confirm actual stock, grade, coating, pack quantity and lead time for each requested full code before ordering.
Can I replace another manufacturer's CNMG R/L-S insert?
Compare the complete insert code and drawing, cutting hand, S geometry, grade, coating and holder fit. A shared CNMG 1204 body size does not guarantee the same chip control or performance; qualify a sample under the actual cutting conditions.
Can I request a custom grade, marking or packaging?
Send the required geometry, carbide grade, coating, marking, label artwork, pack quantity and target application. Feasibility, minimum quantity and delivery time are confirmed in the quotation and approved specification.
◆Guides & Technical References
Our CNC Insert Selection Guide explains insert shape, radius, grade and chipbreaker checks.
For the exact R/L-S drawing, grade-specific cutting data or a price, send the full insert and holder codes.
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.
