Wood fiber/polyethylene composite (WFPEC) is composed of a natural wood fiber and a recyclable polyethylene plastic, which is normally used as an environmental protection composite material. However, better knowledge of chip formation and surface damage mechanism of WFPEC is essential to improve its machinability for extending exterior and interior applications. In this article, machinability of WFPEC was investigated by analyzing the disparity between cutting efficiency and surface quality through a group of orthogonal cutting experiments with change of cutting depth. The chip formation process was recorded by a high-speed camera system with 5000 frames per second. Surface topography was observed by a scanning electron microscope. The results showed that the chip morphology changed from continuous cutting governed by a continuous shearing process under the shallow cutting depth, to a discontinuous cutting governed by plastic fracture under the deep cutting depth ahead of the tool tip. Flattened matrix was the main form of surface topography caused by shallow cutting depth, while matrix-fiber tearing was caused by deep cutting depth. Pullout/fracture and debonding of fibers were related to the fiber orientation angle and the diameter of fiber bundles, but not to the cutting depth. Taken together, the toughness of the workpiece material in the cutting region decreased with the increase in cutting depth. To avoid matrix-fiber tearing, shallow cutting depth should be used during finishing to maintain surface quality. In contrast, pre-cutting can be performed with a deep cutting depth in order to improve the cutting efficiency.

中文翻译：

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正交切割过程中木纤维/聚乙烯复合材料的可加工性

木纤维/聚乙烯复合材料（WFPEC）由天然木纤维和可回收的聚乙烯塑料组成，通常用作环保复合材料。然而，更好地了解 WFPEC 的切屑形成和表面损伤机制对于提高其可加工性以扩展外部和内部应用至关重要。本文通过一组随着切削深度变化的正交切削实验，分析切削效率和表面质量之间的差异，研究了WFPEC的可加工性。芯片形成过程由高速摄像系统以每秒5000帧的速度记录下来。通过扫描电子显微镜观察表面形貌。结果表明，切屑形态由浅切深下由连续剪切过程控制的连续切削转变为刀尖前方深切深下由塑性断裂控制的不连续切削。扁平基体是浅切深引起的表面形貌的主要形式，而基体-纤维撕裂是深切深引起的表面形貌。纤维的拉断/断裂和脱粘与纤维取向角和纤维束直径有关，与切割深度无关。综上所述，切削区工件材料的韧性随着切削深度的增加而降低。为避免基体纤维撕裂，在精加工过程中应使用较浅的切削深度以保持表面质量。相比之下，