TVS SunLoc Nylon Insert Nuts, inch UNC/UNF – 1/4" to 5/8", grades 2, 5 and 8

TVS Sundram Fasteners SunLoc Nylon Insert Nuts, inch UNC/UNF are hexagon nuts with a nylon locking ring, made by Sundram Fasteners Limited to ASME B18.16.6, in inch (UNC/UNF) sizes from 1/4" to 5/8", property classes 2, 5 and 8, supplied in trivalent iridescent and trivalent white. SFL calls the range SunLoc. The nylon insert grips the bolt thread, so the nut resists loosening under vibration without a spring washer or thread locker, and it can be refitted a limited number of times.

SFL's retail price list of October 2026 gives recommended retail list prices from Rs 330 to Rs 2,345 per 100 pieces across the listed sizes; the exact price for your sizes, pitch, property class and finish is confirmed on enquiry.

Jai Enterprises is an authorised distributor of TVS Sundram Fasteners high tensile fasteners and supplies them from Bhilai and Raipur all over Chhattisgarh - Bhilai, Raipur, Durg, Korba, Bilaspur, Raigarh, Jagdalpur, Kanker, Ambikapur and every other district - and across India.

Is this the right one for you?

Check these four things before you order:

• Your thread is inch UNC or UNF (American unified), not BSW/BSF.
• The size you need is within 1/4" to 5/8".
• The joint sees vibration or movement and you want the nut to stay put without a spring washer or thread locker.
• Service temperature stays within the limit of the nylon ring (about 120 degrees C, the ISO 2320 limit for non-metallic inserts); for hot or repeatedly dismantled joints choose the all-metal prevailing torque nut.

List prices (SFL, 1 October 2026)

Prices are SFL's recommended retail list prices effective 1 October 2026, in rupees per 100 pieces, for the standard SunLoc finish. A few sizes are shown; ask us for any other size in the range.

• 1/4" BSW/UNC/UNF (thick): Rs 330 per 100 pieces
• 5/16" BSW/UNC/UNF: Rs 505 (thin) / Rs 470 (thick) per 100 pieces
• 3/8" BSW/UNC/UNF: Rs 685 (thin) / Rs 635 (thick) per 100 pieces
• 1/2" BSW/UNF/UNC (thick): Rs 1,095 per 100 pieces
• 5/8" BSW/UNF/UNC (thick): Rs 2,345 per 100 pieces
• Thin and thick versions as listed (inch series to BS 1083, P type); where one price is shown it is the thick nut
• Thin-type SunLoc nuts are supplied against enquiry only

At a glance

• Brand: TVS Sundram Fasteners (Sundram Fasteners Limited, TVS group)
• Product: SunLoc Nylon Insert Nuts, inch UNC/UNF
• Standard: ASME B18.16.6
• Sizes: 1/4" to 5/8"
• Form: hexagon
• Property class: 2, 5 and 8
• Material: Steel
• Surface finish: trivalent iridescent and trivalent white
• Forging: cold forging
• List price: Rs 330 - 2,345 per 100 pieces (SFL list, 1 October 2026); exact price on enquiry
• Supplied by: Jai Enterprises, Bhilai and Raipur - to every district of Chhattisgarh and across India, +91 9340081159

Specifications and dimensions

• Standard: ASME B18.16.6
• Material: high tensile steel; inch nut grades to SAE J995 (2, 5, 8)
• Property class: 2, 5 and 8
• Surface finish options: trivalent iridescent and trivalent white
• Manufacture: cold forging
• Marking: TVS brand mark on the face and the property class mark
• 1/4": 20 UNC / 28 UNF tpi; across flats 11.12 mm, across corners 12.40 mm, thickness 8.89 mm
• 5/16": 18 UNC / 24 UNF tpi; across flats 12.70 mm, across corners 14.15 mm, thickness 11.63 mm
• 3/8": 16 UNC / 24 UNF tpi; across flats 14.28 mm, across corners 15.96 mm, thickness 12.82 mm
• 7/16": 14 UNC / 20 UNF tpi; across flats 17.46 mm, across corners 19.51 mm, thickness 14.30 mm
• 1/2": 13 UNC / 20 UNF tpi; across flats 19.05 mm, across corners 21.34 mm, thickness 15.82 mm
• 5/8": 11 UNC / 18 UNF tpi; across flats 23.82 mm, across corners 26.70 mm, thickness 18.79 mm
• Note: dimensions are given for 1/4" to 5/8"; 3/4" and 1" UNC are on SFL's price list - ask us
• Source: SFL's technical product catalogue (September 2026 edition) and SFL's digital product catalogue; dimensions in mm

Why choose TVS Sundram Fasteners

• Made by Sundram Fasteners Limited, a TVS group company making high tensile fasteners since 1966: first Indian company with ISO 9000, IATF 16949:2016 certified, Deming Prize 2018 for 17 plants.
• Every lot is backed by a BIS, NABL and ISO/IEC 17025 certified laboratory - tensile, fatigue, torque-tension, salt spray and coating thickness testing - as described in SFL's technical product catalogue (September 2026 edition).
• Made to a named standard - ASME B18.16.6 - with the dimensions published in SFL's technical catalogue, so parts interchange with any other maker's to the same standard.
• The grade mark on each part shows its property class (2, 5 and 8), so site inspection is simple.
• A choice of finishes - trivalent iridescent and trivalent white - for indoor use and mild exposure.
• Keeps the joint tight under vibration without extra lock washers or thread-locking compound.

How to choose and fit

1. Match the thread of the bolt exactly - size and pitch (or threads per inch) - from the table above.
2. Match the grade of the nut to the bolt (nut grade not lower than the bolt grade).
3. Fit a washer under the nut where the joint face is soft, slotted or painted.
4. Tighten to the specified torque with the bolt held; the prevailing torque of the nylon ring is felt before the nut seats - that is normal, and the tightening torque must allow for it.

Where it is used

• automotive and two-wheeler assemblies
• electrical panels, fans and motors
• conveyors, vibrating screens and rotating equipment
• agricultural machinery and trailers
• imported machinery and older plant built to inch standards

Other versions and series

• TVS Sundram Fasteners SunLoc Nylon Insert Nuts, DIN 982 / ISO 7040 - M6 to M27, list price Rs 280 - 15,690 per 100
• TVS Sundram Fasteners SunLoc Nylon Insert Nuts, DIN 985 - M8 to M48, price on request
• TVS Sundram Fasteners SunLoc Nylon Insert Nuts, inch BSW/BSF - 5/16" to 5/8", list price Rs 470 - 2,445 per 100

Related products

• TVS Sundram Fasteners Hex Nuts, inch UNC/UNF - the plain hex nut
• TVS Sundram Fasteners Prevailing Torque Nuts - the all-metal lock nut

Frequently asked questions

What is the price of SunLoc Nylon Insert Nuts, inch UNC/UNF?

SFL's recommended retail list price effective 1 October 2026 runs from Rs 330 to Rs 2,345 per 100 pieces across the listed sizes, for the standard SunLoc finish. The examples above show typical sizes. Call Jai Enterprises on +91 9340081159 with your sizes, grade, finish and quantity for the exact price; other finishes and sizes outside the list are quoted on enquiry.

Can a nylon insert nut be reused?

It can be refitted a few times, but the locking torque falls each time the nylon ring is cut by the thread. For joints that are opened often, or that run hot, use the all-metal prevailing torque nut instead.

Are TVS SunLoc Nylon Insert Nuts, inch UNC/UNF available in Chhattisgarh?

Yes. Jai Enterprises, an authorised distributor of TVS Sundram Fasteners, supplies from Bhilai and Raipur all over Chhattisgarh and across India. Call +91 9340081159 or use the enquiry form.

Can I get a different finish or a non-listed size?

Yes. The standard finishes are trivalent iridescent and trivalent white; other finishes and sizes or lengths outside the list are quoted on enquiry from SFL.

How to order

Call Jai Enterprises on +91 9340081159 or send an enquiry with the sizes, pitch, property class, finish and quantity of SunLoc Nylon Insert Nuts, inch UNC/UNF you need. SFL's list price is Rs 330 - 2,345 per 100 pieces across the listed sizes (SFL list, 1 October 2026); the exact price is confirmed on enquiry. We supply from Bhilai and Raipur all over Chhattisgarh - Bhilai, Raipur, Durg, Korba, Bilaspur, Raigarh, Jagdalpur, Kanker, Ambikapur and every other district - and across India.