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Description
CUTTING WIDTH4 mm
CUTTING DEPTH T MAX18 mm
MAX. BAR DIAMETERØ36 mm
INSERT · 2 EDGESMGMN 400
Left-hand parting tool 25X25 4 mm T18 Varel
Technical data for the holder for Korloy MGMN 400 inserts
| Technical data | |
|---|---|
| Designation | MGEHL 2525-4 |
| Type | holder for parting and external grooving |
| Shank height h | 25 mm |
| Shank width B | 25 mm |
| Overall length L | 150 mm |
| Dimension S (to the insert edge) | 25.4 mm |
| Cutting depth T max | 18 mm |
| Max. parting diameter D max | Ø36 mm |
| Insert pocket | MGMN 400 (width 4 mm) |
| Hand | L – left-hand |
MGEHL 2525-4 – construction and clamping of the 4 mm insert
What this tool can do, screw clamping and a double-edged insert
For parting off workpieces from bar stock and cutting external grooves, use left-hand parting tool 4 mm MGEHL 2525-4 by Varel. The holder accepts a double-edged MGMN 400 carbide insert with a width of 4 mm. The insert is clamped from above by the flexible lip of the head, tightened by a screw. It can be replaced without removing the tool from the tool post.
The insert edge projects 0.4 mm beyond the side of the shank (S = 25.4 mm with B = 25 mm). When cutting close to the chuck, only the cutting edge engages; the shank does not rub against the workpiece face. The 25x25 mm shank, 150 mm long, provides the rigidity required by a narrow cutting edge in an enclosed groove.
The MGMN 400 insert is double-edged: when one edge becomes dull, rotate it by 180° and cut with the other end.
The head forms a thin blade 18 mm long, which determines the cutting depth T max. Behind the blade, the head widens to the full shank width and can no longer enter the 4 mm groove. This sets the limit: the tool parts off bars up to Ø36 mm, or twice T max.
Parting and grooving with the MGEHL 2525-4 tool – typical operations
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
25 mm
WIDTH B
25 mm
LENGTH L
150 mm
DIMENSION S
25.4 mm
T max is measured from the insert tip to the head shoulder. A groove shallower than 18 mm can also be cut in a bar larger than Ø36 mm.
The left panel of the diagram shows the end of the cut: the insert tip is on the bar axis, and the head shoulder touches its surface. The right panel shows cutting edge height: set the edge on the centerline to within ±0.1 mm. Below the centerline, a pip remains; above the centerline, the cutting edge rubs against the material.
MGEHL 2525-4 designation decoder
The four parts of the MGT system designation, read from the left
Designation: MGEHL 2525-4
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.
L
Element 2
hand
hand
Left-hand
L
L
Mirror image of the right-hand MGEHR version with the same dimensions.
2525
Element 3
shank
shank
25x25 mm
2525
2525
The first two digits indicate height h, and the next two indicate width B. Fits a tool post for 25 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 25 · B 25 · L 150 · S 25.4 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 values apply to coated MGMN 400 inserts used with coolant. Use the higher speeds with rigid clamping and short overhang.
| 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 |
| ✓ | Right-hand version MGEHR 2525-4 with the same dimensions |
| ✓ | Other available sizes in the -4 series: MGEHL 2020-4 (T max 18 mm) |
Varel parting tools for MGMN 400 inserts
MGEHR/L 2020-420x20 mm | L 125 mm | T max 18 mm | Ø36 mmR right-hand
←L left-hand
→
←L left-hand
→
Inserts from other grooving systems (DGN, GTN, KGM) require different seats and do not fit this holder. The 4 mm MGEHL 2525-4 left-hand parting tool parts off workpieces from bar stock up to Ø36 mm and cuts external grooves with a width of 4 mm. When the groove width is a dimension with a specified fit, choose an MGGN insert with a tolerance of ±0.025 mm. Groove depth is limited by T max = 18 mm. In series production on automatic and CNC lathes, it parts off workpieces from bar stock in every cycle.
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.
Yes. The holder cuts external grooves 4 mm wide and up to 18 mm deep. An insert with -M or -T geometry also allows turning with the side of the insert, but with a depth of cut up to 0.8 × 4 mm = 3.2 mm per pass.
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 | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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