JETCO Torque Tools Accessories
www.itorque.com
Joint Rate Simulators (run down adapters)
Joint Rate Simulators are used to simulate the tightening of a fastener when testing power tools on a torque tester or transducer. This assembly is needed so the power tool being tested has a chance to spin up to speed and then tighten a fastener with the same or similar characteristics as the application the tool is used on. The joint rate simulator is placed between the power tool and the torque tester or transducer. Power tools have different torque outputs based on the type of joint they are being used on (a result mostly of inertia). For example, if two plates of steel are being fastened together the power tool will build up full power then "slam" the joint together. If two pieces of plastic are being fastened together the tool will slow down while the plastic compresses and have to work harder to generate the torque. These two conditions can be simulated with a joint rate simulator. Inserting varying types of spring washers can create different types of joint simulations. To simulate a hard joint (two pieces of steel) you would remove the springs and use flat washers.
Procedure to Measure Joint Rate On The Application:
Joint rates are divided into three categories: Soft, Medium and Hard.
If the fastener turns more than 360 degrees for the last half of the torque required then it is considered a "soft" joint.
If the fastener turns more than 30 degrees but less than 360 degrees for the last half of the torque required then it is considered a "medium joint".
If the fastener turns less than 30 degrees for the last half of the torque required it is considered a "hard" joint.
You can measure the joint rate of an application by doing the following:
1. Using an accurate torque wrench such as a digital wrench or a dial type wrench apply 50% of the final torque to a fastener. For example if the final torque is 50 ft.lb. tighten the fastener to 25 ft.lb..
2. Mark the head of the fastener and the part with a permanent marker. Put a line on the head of the fastener and the base part so when the fastener moves you can see the distance the two marks have separated.
3. Apply the full torque value. Note the angle the fastener has moved by comparing the separation of the lines.
To recreate this on the tester use a joint rate simulator with the proper spring washer combination that simulates your results. If the joint is hard use solid washers.
Contact JETCO for more information on Joint Rate Simulation.
Phone:626-359-2881