【Pump Technology Edition: Daily Question】March 18, 2020 (Section benefit: 10 Wealth points as a reward for answering correctly before the answers are revealed)
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137. To eliminate the accuracy variations caused by internal stresses in cast iron guides, ( ) treatment must be carried out before machining. A、Ageing B、Tempering ； C. Quenching. Answer to question 136 on March 18, 2020: B. 136. The clearance in rolling bearings is always (B) the original clearance. A. Greater than B. Less than C. Equal to (Answers are released the day before they are announced; a reward of 10 wealth points is given for correct answers before the announcement, 5 wealth points for correct answers after the announcement, and 3 wealth points for just participating). I’ve been a bit busy lately, which means it’s taking some time to post questions and provide feedback on scores. But no matter how busy or late it gets, I will still post questions and respond to everyone. Thank you all for your continued support!
The so-called aging treatment involves heating cast iron or cast steel below its critical temperature and maintaining that temperature for a certain period of time, in order to eliminate the internal stresses in the material and stabilize its dimensions. To save energy, the castings can also be left exposed to the elements, subject to sunlight and rain, allowing the stresses to dissipate gradually; this process is known as natural aging or spontaneous aging. Placing it in a certain temperature is known as artificial aging.