V-COIL thread inserts for UNF, Unified fine thread
UNF has more threads per inch than UNC at the same diameter. It carries better in thin-walled parts and holds preload under vibration — common in automotive and aerospace work. A thread insert restores a stripped thread and can give it a load capacity above that of the original. The stainless steel wire coil is screwed into the hole after it has been drilled out and re-tapped with the STI tool.
VÖLKEL offers 145 versions, from UNF No. 4 x 48 to UNF 1.1/2 x 12.
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All sizes at a glance
145 articles in 2 series. The article number links straight to the tool.
V-COIL Wire thread insert Free running type S
| Threadnominal size | Tapping drillØ in mm | 1.0 D | 1.5 D | 2.0 D | 2.5 D | 3.0 D |
|---|---|---|---|---|---|---|
| UNF No. 4 x 48 | 3 | 08290100 pcs. | 08390100 pcs. | 08490100 pcs. | 08590100 pcs. | 08690100 pcs. |
| UNF No. 6 x 40 | 3.7 | 08291100 pcs. | 08391100 pcs. | 08491100 pcs. | 08591100 pcs. | 08691100 pcs. |
| UNF No. 8 x 36 | 4.4 | 08292100 pcs. | 08392100 pcs. | 08492100 pcs. | 08592100 pcs. | 08692100 pcs. |
| UNF No. 10 x 32 | 5.1 | 08293100 pcs. | 08393100 pcs. | 08493100 pcs. | 08593100 pcs. | 08693100 pcs. |
| UNF 1/4 x 28 | 6.6 | 08225100 pcs. | 08325100 pcs. | 08425100 pcs. | 08525100 pcs. | 08625100 pcs. |
| UNF 5/16 x 24 | 8.2 | 08226100 pcs. | 08326100 pcs. | 08426100 pcs. | 08526100 pcs. | 08626100 pcs. |
| UNF 3/8 x 24 | 9.8 | 08227100 pcs. | 08327100 pcs. | 08427100 pcs. | 08527100 pcs. | 08627100 pcs. |
| UNF 7/16 x 20 | 11.5 | 08228100 pcs. | 08328100 pcs. | 08428100 pcs. | 08528100 pcs. | 08628100 pcs. |
| UNF 1/2 x 20 | 13 | 08229100 pcs. | 08329100 pcs. | 08429100 pcs. | 08529100 pcs. | 08629100 pcs. |
| UNF 9/16 x 18 | 14.8 | 0823050 pcs. | 0833050 pcs. | 0843050 pcs. | 0853050 pcs. | 0863050 pcs. |
| UNF 5/8 x 18 | 16.25 | 0823150 pcs. | 0833150 pcs. | 0843150 pcs. | 0853150 pcs. | 0863150 pcs. |
| UNF 3/4 x 16 | 19.5 | 0823325 pcs. | 0833325 pcs. | 0843325 pcs. | 0853325 pcs. | 0863325 pcs. |
| UNF 7/8 x 14 | 22.75 | 0823510 pcs. | 0833510 pcs. | 0843510 pcs. | 0853510 pcs. | 0863510 pcs. |
| UNF 1" x 12 | 26 | 0823710 pcs. | 0833710 pcs. | 0843710 pcs. | 0853710 pcs. | 0863710 pcs. |
| UNF 1" x 14 | 26 | – | 0833810 pcs. | – | – | – |
| UNF 1.1/8 x 12 | 29 | – | 083965 pcs. | – | – | – |
| UNF 1.1/4 x 12 | 32.5 | – | 083975 pcs. | – | – | – |
| UNF 1.3/8 x 12 | 35.5 | – | 083985 pcs. | – | – | – |
| UNF 1.1/2 x 12 | 38.5 | – | 083995 pcs. | – | – | – |
V-COIL Wire thread inserts Refill pack Free running type S
| Threadnominal size | Tapping drillØ in mm | 1.0 D | 1.5 D | 2.0 D | 2.5 D | 3.0 D |
|---|---|---|---|---|---|---|
| UNF No. 4 x 48 | 3 | 4422110 pcs. | 4432110 pcs. | 4442110 pcs. | 4452110 pcs. | 4462110 pcs. |
| UNF No. 6 x 40 | 3.7 | 4422210 pcs. | 4432210 pcs. | 4442210 pcs. | 4452210 pcs. | 4462210 pcs. |
| UNF No. 8 x 36 | 4.4 | 4422310 pcs. | 4432310 pcs. | 4442310 pcs. | 4452310 pcs. | 4462310 pcs. |
| UNF No. 10 x 32 | 5.1 | 4422410 pcs. | 4432410 pcs. | 4442410 pcs. | 4452410 pcs. | 4462410 pcs. |
| UNF 1/4 x 28 | 6.6 | 4422510 pcs. | 4432510 pcs. | 4442510 pcs. | 4452510 pcs. | 4462510 pcs. |
| UNF 5/16 x 24 | 8.2 | 4422610 pcs. | 4432610 pcs. | 4442610 pcs. | 4452610 pcs. | 4462610 pcs. |
| UNF 3/8 x 24 | 9.8 | 442275 pcs. | 443275 pcs. | 444275 pcs. | 445275 pcs. | 446275 pcs. |
| UNF 7/16 x 20 | 11.5 | 442285 pcs. | 443285 pcs. | 444285 pcs. | 445285 pcs. | 446285 pcs. |
| UNF 1/2 x 20 | 13 | 442295 pcs. | 443295 pcs. | 444295 pcs. | 445295 pcs. | 446295 pcs. |
| UNF 9/16 x 18 | 14.8 | 442305 pcs. | 443305 pcs. | 444305 pcs. | 445305 pcs. | 446305 pcs. |
| UNF 5/8 x 18 | 16.25 | 442315 pcs. | 443315 pcs. | 444315 pcs. | 445315 pcs. | 446315 pcs. |
| UNF 3/4 x 16 | 19.5 | 442335 pcs. | 443335 pcs. | 444335 pcs. | 445335 pcs. | 446335 pcs. |
| UNF 7/8 x 14 | 22.75 | 442355 pcs. | 443355 pcs. | 444355 pcs. | 445355 pcs. | 446355 pcs. |
| UNF 1" x 12 | 26 | 442375 pcs. | 443375 pcs. | 444375 pcs. | 445375 pcs. | 446375 pcs. |
Tapping drill: drill diameter recommended by VÖLKEL (Technical Information “Tapping drill sizes V-COIL”).
