MIM Stainless Steel Smart Lock Deadbolt Mechanism | Precision Lock Tongue Component

This MIM stainless steel smart lock deadbolt is a precision lock tongue component, typically made from SUS304, 17-4PH, or 316L stainless steel. MIM suits it because the complex bolt profile, anti-saw pin recesses, and drive rack form as one strong, precise piece without welds or assembly.

Key specifications

Material	SUS304, 17-4PH, or 316L stainless steel
Surface finish	smooth enough to slide freely
Sintered density	≥7.6 g/cm³
Secondary operations	anti-saw rollers 440C hardened HRC 56–60

What Is the Smart Lock Deadbolt?

If the cylinder is the brain and the motor and gears are the muscles, the deadbolt — often called the lock tongue — is the hand. It is the physical steel bar that extends from the lock body into the door frame strike plate, securing the door against forced entry. In a smart lock, the deadbolt must do everything a traditional deadbolt does — resist kicking, prying, sawing, and bumping — while also moving smoothly under motor power rather than human key torque.

At Precision-mim, we MIM-manufacture smart lock deadbolts and lock tongues in stainless steel. The process produces the full bolt profile — including anti-saw pins, anti-pry shoulders, tapered lead-in, and drive slot — as a single piece with no welds, no assembly, and no weak points.

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MIM Stainless Steel Smart Lock Deadbolt Mechanism | Precision Lock Tongue Component

The Engineering Challenge

A deadbolt seems simple — a rectangular bar of steel. But the details define security:

Anti-saw pins— hardened steel rollers embedded in the bolt body that spin freely when a saw blade contacts them, preventing a cut
Anti-pry shoulder— an undercut geometry that hooks behind the strike plate edge, resisting pry-bar attack
Throw length— typically 25–35 mm projection; must be dead straight to avoid binding
Drive interface— the slot or rack that receives the drive cam from the cylinder or motor gear train
Surface finish— smooth enough to slide freely, rough enough to resist bump-key manipulation

Traditional manufacturing welds or rivets anti-saw pins into a machined bolt body, then grinds the assembly smooth. This creates three problems: the weld is a corrosion weak point, the pin can seize over time, and the assembly cost is high.

MIM solves all three:the bolt body and anti-pin recesses are molded as one piece, hardened roller pins are inserted as loose components (they must spin freely), and the entire bolt comes out of the furnace at final dimensions.

Material Selection

Material	Grade	Key Property
Bolt body	SUS304 or 17-4PH	Strength + corrosion resistance
Anti-saw rollers	440C hardened	HRC 56–60, spin freely under saw attack
Bolt body (commercial)	17-4PH H900	HRC 40–45 for high-security applications
Coastal/outdoor	316L	Maximum chloride corrosion resistance

Deadbolt Design Features

Tapered lead-in— 15–20° chamfer on the bolt nose for smooth strike plate engagement
Anti-friction ribs— raised longitudinal ribs that reduce sliding contact area, lower motor torque requirement
Anti-pry hook geometry— undercut shoulder that engages behind the strike plate
Anti-saw roller recesses— molded pockets for loose hardened steel roller pins
Drive rack— integrated gear rack teeth for direct motor drive (eliminates separate cam)
Position sensor target— molded-in magnet pocket or flag for open/closed position sensing

Material Properties

Property	SUS304	17-4PH H900
Tensile Strength	480–520 MPa	1,310 MPa
Shear Strength (bolt cross-section)	~300 MPa	~750 MPa
Hardness	HRB 70–85	HRC 40–45
Density	≥7.6 g/cm³	≥7.65 g/cm³

Shear strength is the critical security parameter — it determines the force required to snap the bolt through the strike plate under a kick or ram attack.

Quality Assurance

Throw length verification — 100% measurement
Straightness — <0.1 mm bow over bolt length
Hardness testing — batch sample
Function test — slide force measurement, <5N under zero load
Anti-saw pin free rotation — 100% manual spin check
Salt spray — ASTM B117, per material grade

Your smart lock is only as strong as its deadbolt. Our ISO-certified MIM process delivers bolt components with the strength and precision that security demands. See Quality Assurance for certification details.

Designing a smart lock deadbolt or lock tongue? Send your specifications — we'll evaluate MIM manufacturability and recommend the optimal material grade.

Frequently asked questions

What stainless steel grades can the MIM smart lock deadbolt be made from?

The deadbolt body can be produced in SUS304 or 17-4PH stainless steel, with 17-4PH H900 offering HRC 40–45 for high-security applications. For coastal or outdoor use, 316L provides maximum chloride corrosion resistance. Anti-saw rollers use 440C hardened to HRC 56–60 and spin freely under saw attack.

Why is MIM better than welding or riveting anti-saw pins into a machined bolt?

Traditional manufacturing welds or rivets anti-saw pins into a machined bolt body, creating a corrosion weak point, pin seizure risk, and high assembly cost. MIM molds the bolt body and anti-pin recesses as one piece, inserts hardened roller pins as loose components so they spin freely, and delivers the bolt at final dimensions with no welds or assembly.

What design features and tolerances does the MIM deadbolt include?

The one-piece bolt includes anti-saw pin recesses, anti-pry shoulder geometry, a 15–20° tapered lead-in, anti-friction ribs, an integrated drive rack, and a molded-in position sensor target. Throw length is typically 25–35 mm and is 100% verified; straightness is held under 0.1 mm bow over the bolt length, with slide force under 5N at zero load.

How is quality assured on MIM stainless steel deadbolts?

Quality assurance includes 100% throw length measurement, straightness verification under 0.1 mm bow, batch-sample hardness testing, function testing with slide force measurement under 5N at zero load, 100% manual spin checks on anti-saw pins, and salt spray testing to ASTM B117 per material grade. The process is ISO-certified.