T-Bolt for 8 mm T-Slot Aluminium Profiles M6 M8 M10

OEM / ODM Available Free Sample Available RoHS, REACH, material certificate for stainless steel, bolt grade test report

T-bolt with integral T-head for 20, 30 and 40 series aluminium profiles. M5, M6, M8 and M10 threads. Replaces separate T-nut, faster assembly. Carbon steel or stainless steel.

Wholesale Price Quoted per piece, price breaks at 100 / 500 / 1000 per per piece

Material	Carbon steel
Alloy Grade	Carbon steel grade 8.8 / 10.9, stainless A2 / A4
Temper	custom
Section Size	n/a (piece part)
Slot	Fits 6 mm, 8 mm and 10 mm groove widths (20/30/40 series)
Length	Stock 8-30 mm; custom 6-50 mm (6-60 mm M10)
Tolerance	Thread 6g, head width +/-0.1 mm, head thickness +/-0.05 mm
Surface	Zinc plated / stainless steel A2 or A4
MOQ	No MOQ for stock sizes; 500 pieces for custom sizes
Lead Time	Stocked sizes ship in 2 to 3 days; custom sizes about 2 weeks
Loading Port	Shanghai, Ningbo, Qingdao
Supply Ability	Stocked carbon steel sizes in volume; stainless and custom sizes produced to order
Payment Terms	T/T 30 per cent deposit, balance against copy of B/L; L/C at sight for larger orders
Trade Terms	FOB, CIF, CFR, EXW
Certifications	RoHS, REACH, material certificate for stainless steel, bolt grade test report

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01What is a T-bolt?

How is a T-bolt different from a bolt-plus-nut combination?

A T-bolt has a flat T-shaped head formed integrally with the bolt shank. The head slides into the T-slot groove and bears against the slot lip from behind, exactly like a T-nut would. The difference is that there is no separate nut to place, slide or drop into the groove — the head is already on the bolt. You slide the T-bolt into the slot, position it, put the bracket on and tighten the single fastener.

When is a T-bolt better than a bolt plus a separate nut?

When assembly speed is the priority and the fitting position is known. A T-bolt saves one handling step (placing or sliding the nut) per joint. On a frame with 20 joints, that saves about 3 minutes. The trade-off is that the T-bolt head occupies slot depth, so it may not fit in the thinnest-walled profiles, and the head cannot be repositioned without sliding it along the groove like a nut.

Can you still use a nut if you want to?

Yes, a T-bolt works with a separate T-nut too, but that defeats the purpose. The T-bolt head and a T-nut would both be behind the groove lip, and the bolt would pass through both. The standard use is T-bolt head bearing on the groove, with the bracket on the outside and the nut on top of the bracket.

02T-bolt vs bolt-plus-nut: the assembly logic

The T-bolt is a one-piece fastener that combines the functions of bolt and nut. The T-head plays the role of the nut — it bears against the back of the groove lip and resists the clamping force. The bolt shank passes through the bracket, panel or fitting, and a standard hex nut on the outside provides the clamping.

This is different from a bolt-plus-nut combination, where the T-nut is inside the groove and the bolt passes through the bracket from outside. In that case, the T-nut bears on the groove and the bolt head is on the outside. The clamping force path is the same, but the handling is different: two pieces (nut plus bolt) instead of one piece (T-bolt plus plain nut).

Property	T-bolt + plain nut	Plain bolt + T-nut
Pieces per joint	2 (T-bolt, hex nut)	2 (bolt, T-nut)
Nut placement in slot	not needed — head is integral	must place or slide T-nut
Assembly speed	faster (no nut handling)	slower (nut must be positioned)
Head in slot	T-bolt head (flat, fixed)	T-nut body (can slide along slot)
Head on outside	hex nut (can be positioned freely)	bolt head (fixed by bolt length)
Slot depth used	T-head thickness (2.5 to 4.5 mm)	T-nut body height (4 to 6 mm)
Repositioning	must slide T-bolt along groove	must slide T-nut along groove

In practice, both approaches require sliding a component along the groove. The T-bolt saves the step of placing the nut separately, but the T-head still has to be slid to the correct position. The saving is real but smaller than it first appears.

03T-head thickness and slot depth

The T-head has a specific thickness that must fit within the groove depth. The groove depth is the distance from the slot mouth to the back wall of the profile. If the T-head is thicker than the groove depth, it will not seat and the bolt cannot be tightened.

The table below shows the T-head thickness for each series and the minimum groove depth required. The groove depth is set by the profile design and cannot be changed, so the T-bolt must be matched to the series.

Series	Groove width	Groove depth	T-head thickness	Head clearance
20 series	6 mm	7.3 mm	2.5 mm	4.8 mm
30 series	8 mm	9.5 mm	3.5 mm	6.0 mm
40 series	10 mm	12.0 mm	4.5 mm	7.5 mm

Head clearance is the remaining groove depth after the T-head seats. This space is available for cable routing, cover strip legs or other accessories that sit in the groove behind the T-bolt. A thicker T-head (e.g. a 40 series bolt in a 30 series groove) will not seat because the head is thicker than the groove depth.

04Thread sizes and bolt lengths

T-bolts are available in three thread sizes matched to the three standard series. The bolt length determines how thick a bracket or panel stack can be clamped. Standard lengths are stocked; custom lengths are cut and threaded to order.

Series	Thread	Stock lengths (mm)	Custom range (mm)
20 series	M5	8, 10, 12, 15, 20	6 to 30
30 series	M6	10, 12, 16, 20, 25	8 to 40
40 series	M8	12, 16, 20, 25, 30	10 to 50
40 series	M10 (on request)	16, 20, 25, 30	12 to 60

M10 T-bolts are available for 40 series on request but are not stocked. The 40 series groove is wide enough for the M10 T-head, but the bolt torque is limited by the groove wall strength to 35 Nm, not by the bolt grade.

05Bolt grades and torque limits

T-bolts are available in two grades: 8.8 (medium carbon, quenched and tempered) and 10.9 (alloy steel, quenched and tempered). The grade determines the bolt’s tensile strength and the maximum recommended torque. However, the actual torque limit is usually set by the groove wall strength, not the bolt grade.

On a 40 series profile, an M8 grade 8.8 T-bolt can withstand 25 Nm of torque, but the groove wall will start to deform at about 30 Nm. Using a 10.9 bolt does not increase the usable torque — it just means the bolt will not break before the groove deforms.

Thread	Grade 8.8 max (Nm)	Grade 10.9 max (Nm)	Groove limit (Nm)
M5 (20s)	4.5	6.0	5.0
M6 (30s)	9.0	12.0	10.0
M8 (40s)	22.0	30.0	25.0
M10 (40s)	35.0	49.0	35.0

The groove limit column shows the torque at which the groove wall begins to deform. This is the practical maximum torque, regardless of bolt grade. For applications that need higher clamping force, use the centre bore through-bolt instead of the T-slot.

06When to choose T-bolts over bolt-plus-nut

Choose T-bolts

Production frames with many joints — the assembly time saving multiplies
Frames where the fitting position is known before the bolt is inserted
Automated or jig-guided assembly where placing a separate nut is awkward
Joints where the outside of the bracket needs a hex nut (e.g. levelling feet with a threaded post)
When you want to minimise parts count in the fastener kit

Choose bolt-plus-nut

Prototypes where fitting positions may change
Joints where the nut needs to be positioned after the bracket is in place
Frames where the groove depth is shallow and the T-head does not seat
Retrofit work on existing frames that already have T-nuts installed
When you need higher torque than the groove wall allows — use through-bolt in the centre bore

07Failure modes to design out

What goes wrong	Why it happens	Design it out by
T-head does not seat in groove	head thickness exceeds groove depth (wrong series match)	match T-bolt series to profile series; check head thickness vs groove depth
T-bolt slides in groove under load	T-head is narrower than groove width (wrong series match)	use the correct series T-bolt; a 20s T-bolt in a 40s groove will slide
Groove wall deforms under torque	bolt torque exceeds groove wall strength	stay within groove limit torque; use centre bore for higher loads
Bolt loosens under vibration	T-head does not prevent rotation; only friction holds position	use anti-torsion nut-plus-bolt, or add a spring washer under the hex nut
T-head breaks off under lateral load	the head-to-shank junction is the weakest cross section	use grade 10.9 for lateral loads; avoid using T-bolts as shear pins

08What to specify when ordering

Procurement checklist for T-bolts

Confirm the profile series: 20 (6 mm), 30 (8 mm) or 40 (10 mm). The T-head width and thickness must match the groove.
Confirm the thread size: M5, M6 or M8. M10 is available on request for 40 series.
Confirm the bolt length: the thickness of the bracket, panel or fitting stack, plus the nut and any washers.
Confirm the bolt grade: 8.8 is standard for most applications; 10.9 for higher strength. Note that groove limit applies regardless of grade.
Confirm the finish: zinc plated for indoor, stainless steel for corrosive environments.
Specify the quantity per size. Price breaks apply at 100, 500 and 1000 pieces.

09Terms used on this page

T-bolt: A bolt with an integral flat T-shaped head that slides into the T-slot groove and bears against the slot lip, replacing a separate T-nut.
T-head: The flat, rectangular head at the end of a T-bolt. Its width matches the groove width and its thickness must be less than the groove depth.
Groove depth: The distance from the slot mouth to the back wall of the T-slot. It determines the maximum T-head thickness that will seat.
Bolt grade: A designation of bolt tensile strength. Grade 8.8 has a tensile strength of 800 MPa; grade 10.9 has 1000 MPa.
Groove limit: The maximum bolt torque before the groove wall begins to deform. This is usually lower than the bolt grade limit.
Through-bolt: A long bolt that passes through the central bore of the profile, independent of the T-slots. Used for loads that exceed the groove wall strength.

10Questions buyers ask

Do T-bolts replace T-nuts entirely?

No. T-bolts and T-nuts serve different assembly strategies. A T-bolt has the head on the bolt, so there is no nut inside the groove. A T-nut sits inside the groove and a plain bolt passes through from outside. Both are valid; the choice depends on assembly speed and fitting position requirements.

Can I use a T-bolt from one series in a different series groove?

No. The T-head width and thickness are matched to a specific groove width and depth. A 20 series T-bolt head will slide sideways in a 40 series groove, and a 40 series T-bolt head will not fit in a 20 series groove at all.

What bolt lengths are available?

Stock lengths for M5 are 8 to 20 mm, for M6 are 10 to 25 mm, and for M8 are 12 to 30 mm. Custom lengths from 6 to 50 mm (M5 to M8) and 12 to 60 mm (M10) can be cut and threaded to order.

Are stainless steel T-bolts available?

Yes, in A2 and A4 stainless steel. The T-head is machined from the same stainless bar, so there is no galvanic issue. Stainless T-bolts are used in food-grade, cleanroom and marine applications.

What is the maximum torque?

The groove wall strength sets the practical limit: 5 Nm for M5 in 20 series, 10 Nm for M6 in 30 series, 25 Nm for M8 in 40 series, and 35 Nm for M10 in 40 series. Higher bolt grades do not increase the usable torque.

Do you supply the matching hex nuts?

Yes. We supply standard hex nuts in the same thread sizes and materials, and spring washers for anti-loosening. Specify the thread, material and quantity when ordering.

What we need to quote T-bolts

The profile series (20, 30 or 40) and the groove width for each joint.
The thread size: M5, M6, M8 or M10 (40 series only).
The bolt length for each fitting: bracket thickness plus nut and washer allowance.
The bolt grade: 8.8 standard or 10.9 high-strength.
The material: carbon steel zinc plated, or stainless steel.
The quantity per size, with total across all sizes.

Send those six items and the quotation comes back with the unit price at each quantity break and the lead time for stocked and custom lengths. Browse the full connecting elements range for related fasteners.

Need T-bolts quoted for your frame build?

Send the series, thread, length, grade and quantity. We quote unit price at quantity breaks and can supply matching hex nuts and washers.

Request a quotation