How to choose a pneumatic wrench?
What is the guideline when buying a pneumatic impact wrench?
Let’s skip the price criteria, and let’s start with technical issues, those relating first of all details that we want to twist or spin. Why is it so important? Well, knowledge about the threaded connection will allow you to choose the right moment of strength. Where to find information on tightening forces for individual thread sizes? It is worth using the tables (at the end of the article)
What is worth seeing?
How much is 1Nm? This is a newton meter one meter. For illustration, it is approx. 0.10 kg applied to the end of the 1m long section (1kG ≈ 9.81N). Now assume that the M8 screw in class 5.8 should be tightened with a force of 15 Nm. This means that the arm with a length of 1 meter should be loaded with a mass of approx. 1.5 kg. Another example. In a passenger car, the wheel should be tightened with a torque of e.g. 90Nm. A weight of approx. 9 kg should therefore be applied to the 1-meter arm. Unfortunately, unfortunately, threaded connections of passenger car wheels are tightened with too much force. Using a pneumatic impact wrench for this operationgreatly speeds up the work, but the unskilful use of this tool can prevent the customer from manually unscrewing and changing the wheel in the field. In addition, using the maximum force of the pneumatic tool can lead to damage to the rim, and thus to a road accident. Failure to turn the key knob to the minimum tightening value is the most common mistake made at tire change shops. Then, checking the connection with the torque wrench gives an erroneous reading.
And here begins to appear the answer to the question, where from the market so many “strong” impact keys. Can you really get 1400 Nm from a half-inch key with a weight of 2.2 kg? Recall. 1400Nm or about 140kg of weight on the arm with a length of 1m. It should be emphasized that impact wrenches do not have a certain force, but only allow loosening or tightening the threaded connection in the time interval . In this way, the half-inch key is able to loosen the connection tightened with force, say, 1400Nm – but the time allocated for this operation will not be satisfactory, if the unscrewing is successful.