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Description
FINISHED THREADM20 × 2.5
VARIANT2×D (40 mm)
MATERIALStainless steel
SYSTEMV-Coil
M20 2xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M20 2×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M20 × 2.5 |
| Thread pitch P | 2.5 mm |
| Length variant | 2×D |
| Insert height | 40 mm |
| Repair system | V-Coil |
| Compatible tap | M20 4H V-Coil |
| Pre-drilled hole | Ø20.5 mm |
The M20x2.5 V-Coil thread repair insert made from Helicoil-type stainless steel wire restores a damaged thread in a machine body. When installed in a hole tapped with a thread repair tap, it creates a fully functional M20 thread for a standard screw. It requires neither a larger screw nor replacement of the entire component. The 2xD version with a height of 40 mm is selected for soft materials and more heavily loaded joints. The design complies with DIN 8140 form A (free-running).
M20 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M20 × 2.5
1Prepare the hole
diameter: Ø20.5 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 2×D
✓Restore the joint
thread: M20 × 2.5
Screw in the insert using an installation tool — do not stretch it or twist it sideways.
Practical installation checks
A clean hole is essential for straightforward installation — remove chips and coolant residue. Install the insert with an installation tool, without forcing or tilting it. The top coil should sit 1/4–1/2 of a turn below the material surface. Break off the tang with a punch; always remove it from a blind hole.
Helicoil-type insert made from diamond-section wire – construction and operating principle
How the insert stays in the hole
The wire has a diamond-shaped cross section: one edge acts as a screw in relation to the hole, and the other as a nut in relation to the screw being installed. The free coil is slightly larger than the thread in the hole; as it is screwed in, it contracts elastically, then expands upon release and locks permanently in place without adhesive or additional components. Cold-rolled wire with a minimum tensile strength of 1400 MPa produces a thread that is harder and smoother than one cut directly into the material.
Why a standard M20 tap cannot prepare the insert hole
A pitch of 2.5 mm means a wire thickness of approx. 1.62 mm (the 0.65 × P rule).
The installation thread for the insert is therefore approx. 23.25 mm in diameter — approx. 3.2 mm larger than the nominal 20 mm of an M20 thread.
It can only be prepared with a tap M20 4H V-Coil after drilling Ø20.5 mm; after repair, the screw engages a standard thread M20 × 2.5.
M20 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 2xD version
The insert is suitable for steel, stainless steel, cast iron, and aluminum, as well as magnesium and plastics. In each of these materials, it restores a thread of tolerance class 6H. The version 2xD is standard for aluminum and moderately loaded joints. The shorter 1.5xD insert is selected for steel and shallow holes. The longer 2.5–3xD insert is used in soft materials and with screws of property class 8.8 and higher. The insert reinforces threads in applications such as large machine bodies, where the parent material determines load capacity. The first thread turn then carries approximately half the force, as shown in the load distribution table below.
Thread strength: how much load each turn carries
| Thread turn | Standard thread (without an insert) | Thread with a V-Coil insert |
|---|---|---|
| 1 (first from the screw head) | 50% | 30% |
| 2 | 25% | 22% |
| 3 | 12% | 17% |
| 4 | 6% | 13% |
| 5 | 3% | 10% |
| 6 | 2% | 8% |
How to read the table: when the screw is tightened, each thread turn carries part of its load. In a standard thread, the first turn carries as much as 50% of the load — and it strips first. With an insert, the same turn carries only 30% because the load is distributed over the entire thread length. Catalog data from wire thread insert manufacturers.
M20 2×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M20 with a pitch of 2.5 mm.
✓Tap: special M20 4H V-Coil thread repair tap.
✓Tap drill hole: Ø20.5 mm drill bit.
▲Depth: space for an insert 40 mm high and proper seating.
▲
What to remember before repair
The insert requires an STI thread cut with a V-Coil system thread repair tap — a standard M20 tap cuts a smaller thread in which the insert cannot be seated. The free-running version does not lock the bolt: for joints exposed to vibration, use threadlocker or a screw-locking insert.
After the V-Coil M20 2xD thread repair insert is installed, the screw determines the load limit of the joint, rather than the thread in the part. The hole must accommodate the 40 mm insert (2 × 20 mm), including the correct recess below the surface. In addition to repairs, the insert is suitable for reinforcing threads during manufacture.
Frequently asked questions
The length is selected according to the parent material and screw property class. The weaker the material and the stronger the screw, the longer the insert: 1.5xD for steel, cast iron, and shallow holes, 2xD as the standard for aluminum, and 2.5–3xD for soft materials and screws of property class 8.8 and higher. This insert has a length of 2xD.
The top coil of the insert should sit 1/4 to 1/2 of a turn below the material surface. After installation, the installation tang is broken off with a punch. In a blind hole, the broken fragment must be removed.
No, the insert requires an STI thread with a diameter of approximately 23.25 mm. A standard M20 thread measures 20 mm, making it approximately 3.2 mm too small. The hole is drilled to Ø20.5 mm and tapped with an M20 4H V-Coil tap.
Yes, the free-running version can be used with threadlocker or a self-locking nut. Under severe vibration, screw-locking inserts conforming to DIN 8140 form B are used. Their polygonal coil locks the screw in place.
Product accessories
Drill 20.5 Cobalt NWKc HSSE DIN 345
Reference: 0000008560 In stock < 10 items
€35.53
€43.70 brutto
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| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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