Slotted Round Nut (DIN 981)

Question 1: What is DIN 981 lock nut?

Answer: The DIN 981 lock nut is a type of Rolling Bearing Locknut, typically paired with a spring lock washer to enhance its locking effect. This nut, also known as a shaft nut, is primarily used to prevent vibration from causing bearings, bushings, pulleys, and gears to shift on a threaded shaft or spindle. Its sides are slotted, allowing it to be tightened and loosened using a hook wrench or socket wrench.

Question 2: What is DIN 981 applied in?

Answer: The DIN 981 lock nut is mainly used in mechanical transmission and rotating components that require reliable axial fixation and vibration resistance. Its typical application areas are summarized in the table below:

Question 3: What are DIN 981 Materials?

Answer: Common materials for DIN 981 lock nuts include:

• Standard Material: Carbon steel. Carbon steel bearing nuts are strong and wear-resistant.

• Other Optional Materials:

  • Stainless Steel A2 (AISI 304): Offers good general corrosion resistance and is suitable for mildly corrosive environments.

  • Stainless Steel A4 (AISI 316): Contains molybdenum, providing superior corrosion resistance (particularly against pitting and chemical corrosion), making it suitable for more demanding conditions such as marine or chemical environments.

  • Additionally, the nuts may be made from other alloy steels or undergo surface treatments (e.g., zinc plating, black oxide) as required.

Question 4: How to install DIN 981 lock nuts?

Answer: Follow these steps to install DIN 981 lock nuts:

1. Prepare Tools: Select an appropriate hook wrench or socket wrench.

2. Pair with Washer: It is generally recommended to pair the nut with a DIN 5406 standard spring lock washer for optimal anti-loosening performance.

3. Tighten the Nut: Screw the nut onto the shaft threads to the desired position and tighten it using the wrench. For applications requiring precise adjustment, note that finer threads allow for greater control during adjustments.

4. Secure with Washer: Once the nut is tightened, install the spring lock washer, engaging its inner tab into the nut’s slot and its outer tab into the shaft’s keyway or against an adjacent structure to achieve mechanical locking.

Question 5: How to remove DIN 981 lock nuts?

Answer: Follow these steps to remove DIN 981 lock nuts:

1. Release Washer Lock: First, use an appropriate tool (e.g., a screwdriver or needle-nose pliers) to straighten the locking tabs (both inner and outer) of the spring lock washer, disengaging them from the nut’s slot and the shaft/structure.

2. Loosen the Nut: Use a hook wrench or socket wrench to turn the nut counterclockwise and unscrew it from the shaft.

3. Remove the Washer: After removing the nut, take off the spring lock washer.
   Note: Avoid using excessive torque or improper tools during removal to prevent damage to the nut’s slots or the shaft threads.

Download DIN 981 Dimensions pdf and  DIN 981 Weight Chart  or views online

Active Stock List (All items are currently in stock)：

PIC	PRODUCT	SIZE	GRADE	FINISH	THREAD
	DIN 981 steel zinc plated	M8-M280	14H Untempered Grade	zinc plated	Fine
	DIN 981 steel Black	M8-M280	14H Untempered Grade	Black	Fine
	DIN 981 plain A2 stainless steel	M8-M280	A2 Grade	Natural	Fine