為了減少系統的早期失效，機床制造廠可以對控制元件進行篩選，即使每臺元件在實際使用條件下連續工作一定次數，把失效產品排除，以減少裝到系統中的元件早期失效。元件進入耗損失效期以后，失效率將明顯上升。為了防止這種情況影響系統的可靠性，可以在有效壽命（或偶然故障期）將結束時，不管元件是否損壞，也進行更換。采用篩選和預防性更換，可以保證系統中的元件工作在偶然失效期內，在這個前提下才可以用元件的偶然失效率來計算系統的失效率。

在選擇方案時，應考慮盡量減少控制元件數、接點數和焊點數，以降低系統的失效率。采用可編程控制器（PC）來代替由繼電器等組成的控制柜可以提高系統的可靠性。在比較可編程序控制器和繼電器控制柜兩種方案時，除了購置價格以外，還應充分估計前者在提高可靠性、縮短開發周期和減小工作量以及節省維修時間等有利因素。

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