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Description
CUTTING WIDTH4 mm
CUTTING DEPTH T MAX18 mm
MAX. BAR DIAMETERØ36 mm
INSERT · 2 EDGESMGMN 400
Parting tool 20X20 4 mm T18 Varel
Technical data for the holder for Korloy MGMN 400 inserts
| Technical data | |
|---|---|
| Designation | MGEHR 2020-4 |
| Type | holder for parting and external grooving |
| Shank height h | 20 mm |
| Shank width B | 20 mm |
| Overall length L | 125 mm |
| Dimension S (to the insert edge) | 20.4 mm |
| Cutting depth T max | 18 mm |
| Max. parting diameter D max | Ø36 mm |
| Insert pocket | MGMN 400 (width 4 mm) |
| Hand | R – right-hand |
MGEHR 2020-4 – how it works with MGMN inserts
What this tool can do, screw clamping and a double-edged insert
Parting tool 4 mm MGEHR 2020-4 (Varel) parts off bars up to Ø36 mm and cuts external grooves. It uses MGMN 400 carbide inserts, clamped from above by the head's flexible lip. The clamping screw tightens the lip, and the insert can be replaced in a matter of seconds.
The insert is supported by the narrow blade of the head, 18 mm long — this is the cutting depth T max. Beyond this point, the body widens to the shank width, so only the blade fits into the 4 mm slot. This limits the tool to parting off bars up to Ø36 mm, or twice T max.
Dimension S = 20.4 mm means that the cutting edge projects 0.4 mm beyond the side of the 20 mm wide shank. This allows cutting close to the chuck jaws without the shank rubbing against the workpiece face. The 20x20 mm shank with a length of 125 mm is a common size for tool posts on conventional and CNC lathes.
The MGMN 400 insert has two cutting edges at opposite ends. When the first becomes dull, rotate the insert by 180° and use the second.
Applications of the 4 mm parting tool – parting off workpieces and grooving
Parting – cutting a part off a bar
The blade enters the bar all the way to the axis and the part separates. Bars up to Ø36 mm, a 4 mm kerf, and material loss limited to the insert width.
Cutting external grooves
A 4 mm groove between shaft shoulders or a retaining ring groove at the end of a journal, up to 18 mm deep. Cut wider grooves with several adjacent passes.
Screw clamping from above
The screw pulls the head's flexible lip down against the insert. The insert can be replaced without removing the tool from the tool post.
Double-edged insert
MGMN 400 has a cutting edge at both ends. One edge dull? Rotate the insert by 180° and use the other.
Material loss: 4 mm
Each parting cut turns only 4 mm of bar into chips. For 100 parts, this consumes 10 cm less bar than a tool with a 5 mm insert.
Dimensions and cutting reach – dimensional drawing
Side view and top view
HEIGHT h
20 mm
WIDTH B
20 mm
LENGTH L
125 mm
DIMENSION S
20.4 mm
Measure T max from the insert tip to the point where the blade transitions into the wider head. Grooves up to 18 mm deep can also be cut in bars larger than Ø36 mm.
At the end of the cut, the insert tip is at the bar centerline and the shoulder of the head touches the bar surface. The second panel shows the cutting edge height: the edge must be on the centerline within ±0.1 mm. An edge below center leaves a pip; above center, it rubs against the material.
Decoding the MGEHR 2020-4 designation
The four parts of the MGT system designation, read from the left
Designation: MGEHR 2020-4
MGEH
Element 1
holder type
holder type
For parting
MGEH
MGEH
External grooving and parting holder for the MGT insert system, with screw-operated top clamping.
R
Element 2
hand
hand
Right-hand
R
R
Standard configuration with the workpiece clamped in the chuck to the left of the tool. The mirror-image version is designated MGEHL.
2020
Element 3
shank
shank
20x20 mm
2020
2020
The first two digits indicate height h, and the next two indicate width B. Fits a tool post for 20 mm tools.
-4
Element 4
insert width
insert width
4 mm
-4
-4
The number after the hyphen is the insert width in millimeters. The pocket accepts MGMN 400 inserts, and T max is 18 mm (bars up to Ø36 mm).
MGT system catalog convention, not ISO 5608 · dimensions: h 20 · B 20 · L 125 · S 20.4 mm
Parting data – speeds and feeds for a 4 mm insert
Starting values with coolant; refer to the insert grade data sheet for definitive data
The table provides starting values for coated MGMN 400 inserts with coolant. Select the upper speed range when clamping is rigid and tool overhang is short.
| Workpiece material | Vc [m/min] | fn [mm/rev] |
|---|---|---|
| PCarbon steel | 120–200 | 0.07–0.15 |
| PAlloy steel | 130–180 | 0.07–0.15 |
| PHardened steel | 70–130 | 0.07–0.12 |
| MStainless steel | 120–160 | 0.07–0.15 |
| KCast iron | 130–210 | 0.07–0.15 |
Starting spindle speed: n = (1000 × Vc) / (π × D). For a Ø36 mm carbon steel bar at Vc = 170 m/min: n = (1000 × 170) / (3.14 × 36) ≈ 1500 rpm. At constant spindle speed, the cutting speed decreases to zero at the centerline, so enable constant surface speed (G96) with a spindle speed limit on a CNC lathe.
▲
Operating limitations
Do not part off bars larger than Ø36 mm: the shoulder of the head will contact the material before the cutting edge reaches the centerline. Keep overhang from the tool post as short as possible. Over the final 2 mm before the centerline, reduce the feed by as much as 75% and direct coolant straight into the cut.
Installing the MGMN 400 insert in 3 steps
1Loosen
the clamping screw by 2–3 turns
2Seat
clean the pocket, slide the insert in until fully seated
3Tighten
and check that the cutting edge is on the lathe centerline ±0.1 mm
✓Ready
parting off bars up to Ø36 mm
Cutting insert not included
COMPATIBLE WITH:
| ✓ | MGMN 400 parting inserts (Korloy MGT system) – width 4.0 mm, length 21 mm, height 4.8 mm |
| ✓ | Left-hand MGEHL 2020-4 version with the same dimensions |
| ✓ | Other sizes in the -4 series available: MGEHR 2525-4 (T max 18 mm) |
Varel parting tools for MGMN 400 inserts
MGEHR/L 2525-425x25 mm | L 150 mm | T max 18 mm | Ø36 mmR right-hand
←L left-hand
→
←L left-hand
→
Inserts from other grooving systems, such as DGN, GTN or KGM, do not fit the pocket. The 4 mm MGEHR 2020-4 parting tool parts off carbon steel, alloy steel, stainless steel and cast iron when the insert grade matches the material. The limit remains a bar diameter of Ø36 mm. When parting off hardened steel reduce the speed to 70–130 m/min. In metalworking and fabrication shops, it parts off pins, spacers and bushings from bar stock.
Frequently asked questions
An MGMN 400 parting insert (Korloy MGT system) with a width of 4.0 mm, length of 21 mm and height of 4.8 mm. It is double-ended, so each insert provides two cutting edges. DGN, GTN and KGM inserts do not fit this pocket.
Ø36 mm, or twice the cutting depth T max = 18 mm. Larger bars require a holder with a greater cutting depth T max. Grooves shallower than 18 mm can also be cut on larger diameters.
The right-hand R version is standard: the workpiece is held in the chuck to the left of the tool. Choose the left-hand L version (MGEHL 2020-4) when the workpiece is clamped on the opposite side of the tool or when required by your lathe's tool post arrangement. Both versions have identical dimensions.
A pip remains when the cutting edge is not on the lathe centerline. Set it within ±0.1 mm and check that the insert is fully seated in the pocket. Over the final 2 mm before the centerline, reduce the feed by as much as 75%.
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| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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