薄板工件研磨製程中，隨著工件厚度減小或長度增加，在相同預應力之前提下，易使得工件產生過大之預變形，而常面臨到工件平行度難以掌握之困難。本文定義工件初始平行度為尚未進行磨削前之平行度，薄板工件容易因夾持條件之影響受到過大的預應力產生過大的彈性預變形，使得磨削後彈性預變形再度被釋放，而被釋放之彈性預變形即為加工後工件之平行度。
本文以樑變形理論為基礎，考慮磁吸附力及工件剛性，假設磁吸附力為平均分佈力，建立薄板工件預變形量之預估模式。接著探討工件厚度、面積對磁吸附力的影響，同時透過磁力座之輸入電流監測吸附力的大小，快速預測薄板工件受到之預應力；並將工件受到之預應力及工件厚長比引入薄板工件預變形量預估模式進行實驗，驗證模式之準確性。透過預變形量預測模式控制工件結構剛性及預變形量，針對不同初始平行度之工件選擇適當的吸附力，使長300mm、厚長比約0.04之薄板工件平行度提升至20μm。

Thin plates with same pre-stress might lead the pre-deformation too large after grinding process especially when plate thickness decreases or length increases. For the reason, the parallelism of the plate could not promote effectively. This research defines the initial parallelism as the parallelism before grinding. The thin plate is easy to be affected by clamping method with too large pre-stress, and then induce too large elastic pre-deformation. At last, the elastic pre-deformation will be released after grinding, and the released elastic pre-deformation is the parallelism of the thin plate.
This research proposes the model based on beam deformation theory in order to predict the pre-deformation of thin plates related to the magnetic attraction. In this model, we consider the plate rigidity and magnetic attractive force, assuming the magnetic attractive force is uniform force. This method takes the input current of magnetic chuck as indicators of the level of magnetic attractive force, and then discusses the effect of thickness and contact area on magnetic attractive force. Via above, the pre-stress of thin plate be predicted effectively. Based on the pre-deformation prediction model integrated thickness-to-length ratio and pre-stress of thin plate, grinding experiments are performed to verify the accuracy. By the model, the plate structural rigidity and pre-deformation could be control. Depends on initial parallelism of the plate select appropriate magnetic attractive force that improve the parallelism of thin plate with 300mm long、0.4 thickness-to-length ratio to 20μm.

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