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Description
GROOVE WIDTH3 mm
GROOVE DEPTH T MAX6 mm
MIN. BORE DIAMETERØ25 mm
INSERT · 2 EDGESMGMN 300
Left-hand grooving boring bar 20 mm 3 mm Varel
Technical data for the boring bar for Korloy MGMN 300 inserts
| Technical data | |
|---|---|
| Designation | MGIVL 2520-3 |
| Shank diameter d | Ø20 mm |
| Height to flat h | 18 mm |
| Overall length L | 150 mm |
| Head length l | 45 mm |
| Dimension f (centerline – cutting edge) | 15.6 mm |
| Groove depth T max | 6 mm |
| Minimum bore diameter D min | Ø25 mm |
| Insert pocket | MGMN300-M (width 3 mm) |
| Coolant supply | internal channel in the shank |
| Hand | L – left-hand (right-hand version: MGIVR 2520-3) |
MGIVL 2520-3 – operation with an MGMN 300 insert
Round shank with a flat, screw clamp, and double-ended insert
Left-hand grooving boring bar 3 mm MGIVL 2520-3 is a Varel tool for cutting internal grooves in holes from Ø25 mm. The MGMN 300 carbide insert is held by a screw clamp: the BHA0512 screw pulls the flexible lip of the head against the insert. Insert replacement takes a dozen or so seconds, without removing the tool from the holder.
The shank is a Ø20 mm bar, 150 mm long, with a flat machined to a height of h = 18 mm. The flat locates the cutting edge in the reduction sleeve or V-block tool holder, so the insert edge returns to the same height each time it is clamped.
The 45 mm long head carries an insert oriented radially outward. The cutting edge projects 6 mm beyond the shank profile, which defines the groove depth T max. The manufacturer specifies a minimum hole diameter of D min = Ø25 mm for this holder – the diameter at which the shank fits into the hole together with the protruding insert.
The shank has a coolant channel leading to the head. The jet reaches the cutting edge directly and flushes chips out of the hole, which is critical to insert life in internal grooving.
The MGMN 300 insert is double-ended. When one edge becomes dull, rotate it 180° and use the other end.
What this tool can machine – grooves in bores
Internal groove in a single pass
A 3 mm groove for a retaining ring, seal, or undercut in a bore, up to 6 mm deep. The insert feeds radially into the wall to the specified depth.
Groove wider than the insert
Two adjacent passes, with side turning between them at a depth of up to 0.8 × 3 mm = 2.4 mm. The -M or -T geometry allows side cutting.
Screw clamp
The BHA0512 screw pulls the flexible lip of the head against the insert. Insert replacement without removing the tool from the holder.
Double-edged insert
MGMN 300 has a cutting edge at both ends. One edge dull? Rotate the insert by 180° and use the other.
Bores from Ø25 mm
The Ø20 mm shank with its protruding cutting edge fits into holes from Ø25 mm. A smaller hole will not provide enough clearance for the full groove depth of 6 mm.
Dimensions and grooving reach – dimensional drawing
Top view, enlarged head detail, and end view in a D min bore
DIAMETER d
Ø20 mm
HEIGHT h
18 mm
LENGTH L
150 mm
DIMENSION f
15.6 mm
Dimension f = 15.6 mm is the distance from the shank centerline to the cutting edge. Dimension T max = 6 mm indicates the catalog grooving reach; the enlarged detail shows it from the head profile to the cutting edge. The end view shows the tool in a Ø25 mm bore: the cutting edge reaches the wall, with only working clearance remaining on the opposite side of the shank.
The tool enters through the bore opening, and the insert cuts radially into the wall to the groove depth. Chips have little room inside the bore, so direct coolant onto the insert and retract it every few millimeters. Set the cutting edge at the bore centerline height within ±0.1 mm.
MGIVL 2520-3 designation decoder
Four parts of the Varel code read from the left
Designation: MGIVL 2520-3
MGIV
Element 1
holder type
holder type
For internal grooves
MGIV
MGIV
Varel series using the Korloy MGIV configuration: round shank with a coolant channel and screw clamping. The external parting counterpart has the code MGEH.
L
Element 2
hand
hand
Left-hand
L
L
Mirror image of the right-hand version, for operation with the opposite feed direction or spindle rotation. The R version has the code MGIVR 2520-3.
2520
Element 3
hole and shank
hole and shank
Ø25 / Ø20 mm
2520
2520
Two numbers read as a pair: 25 – minimum hole diameter, 20 – shank diameter. The flat at h = 18 mm locates the cutting edge in the holder.
3
Element 4
insert pocket
insert pocket
MGMN 300
3
3
The number after the hyphen is the groove width in millimeters, identifying the seat for an MGMN 300 insert. The same part of the MGEHR code identifies the same seat.
Varel catalog convention (Korloy MGIV configuration), not ISO 5610 · dimensions: d Ø20 · h 18 · L 150 · f 15.6 mm
Internal grooving cutting data – speeds and feeds for a 3 mm insert
Starting values with coolant; refer to the insert grade data sheet for definitive data
Values apply to coated MGMN 300 inserts when machining with coolant. Chips have less room inside a bore than outside, so start in the lower half of the feed range and keep tool overhang as short as possible.
| Workpiece material | Vc [m/min] | fn [mm/rev] |
|---|---|---|
| PCarbon steel | 140–190 | 0.07–0.15 |
| PAlloy steel | 120–160 | 0.07–0.15 |
| PHardened steel | 60–120 | 0.07–0.12 |
| MStainless steel | 120–160 | 0.07–0.15 |
| KCast iron | 150–200 | 0.07–0.15 |
Calculate spindle speed from the bore diameter, not the shank diameter: n = (1000 × Vc) / (π × D). For a Ø25 mm bore in carbon steel at Vc = 170 m/min: n = (1000 × 170) / (3.14 × 25) ≈ 2170 rpm. For a Ø60 mm bore, approximately 900 rpm is sufficient because the same cutting speed applies over a larger circumference.
▲
Operating limitations
Do not enter a bore smaller than Ø25 mm: the shank will contact the wall before the cutting edge reaches the full groove depth. Keep overhang from the holder as short as possible, approximately up to 4 × d = 80 mm, because a longer steel bar starts to vibrate and chips the insert corner. For a retaining ring groove, check the insert width with a caliper: the groove must be wider than the ring by the clearance specified in the ring standard, rather than equal to the insert width.
Installing the MGMN 300 insert in 3 steps
1Loosen
the BHA0512 screw with a wrench L4.0, 2–3 turns
2Seat
clean the pocket, slide the insert in until fully seated
3Tighten
and check that the cutting edge is at bore centerline height ±0.1 mm
✓Ready
grooves in bores from Ø25 mm
Cutting insert not included
COMPATIBLE WITH:
| ✓ | MGMN 300 grooving inserts – width 3 mm, length 21 mm, height 4.8 mm |
| ✓ | BHA0512 clamping screw (spare part) and L4.0 wrench |
| ✓ | Mirror-image version MGIVR 2520-3 (MGIVR 2520-3) with the same dimensions |
| ✓ | Holders for a Ø20 mm round shank with a flat: reduction sleeve or V-block tool holder |
Varel grooving boring bars and parting tools for MGMN 300 inserts
MGIVR/L 3125-3Ø25 mm | Ømin 31 mm | L 200 mm | T max 6 mmR right-hand
←L left-hand
→
←L left-hand
→
MGIVR/L 3732-3Ø32 mm | Ømin 37 mm | L 250 mm | T max 6 mmR right-hand
←L left-hand
→
←L left-hand
→
MGEHR/L 1616-316x16 mm | L 100 mm | S 16.35 mm | T max 18.5 mmR right-hand
←L left-hand
→
←L left-hand
→
MGEHR/L 2020-320x20 mm | L 125 mm | S 20.4 mm | T max 18 mmR right-hand
←L left-hand
→
←L left-hand
→
MGEHR/L 2525-325x25 mm | L 150 mm | S 25.4 mm | T max 18 mmR right-hand
←L left-hand
→
←L left-hand
→
MGEHR/L 3232-332x32 mm | L 170 mm | S 32.4 mm | T max 18 mmR right-hand
←L left-hand
→
←L left-hand
→
The 3 mm MGIVL 2520-3 left-hand grooving boring bar cuts grooves 3 mm wide and up to 6 mm deep in holes from Ø25 mm, machining carbon steel at a cutting speed of 140–190 m/min and a feed of 0.07–0.15 mm/rev. In hydraulic and pneumatic applications, it can produce internal grooves for sealing and retaining rings in bushings and cylinders. Inserts from other grooving systems, such as DGN or KGM, use different pockets and do not fit this holder.
Frequently asked questions
An MGMN 300 grooving insert with a width of 3 mm, a length of 21 mm and a height of 4.8 mm. It is double-edged, so one insert provides two cutting edges. DGN, GTN and KGM inserts do not fit this seat.
Ø25 mm. This is the catalog value for a Ø20 mm shank with a protruding cutting edge. A smaller hole will not provide enough clearance for the full groove depth. MGIVL 3125-3 works in larger holes (from Ø31 mm), and this tool has no restrictions there.
Start at approximately 2170 rpm for carbon steel, at Vc = 170 m/min with a 3 mm insert. Calculate spindle speed from the bore diameter, so approximately 900 rpm is sufficient for Ø60 mm. For stainless steel, use Vc 120–160 m/min.
Up to 6 mm deep, which is T max. In a single pass, the groove width equals the insert width of 3 mm; wider grooves require adjacent passes and side turning. For grooves deeper than 3 mm, retract the insert every few millimeters to clear chips from the bore.
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| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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