## 1 Introduction  
Traditional biomedical stents are made from stainless steel and nickel-titanium alloy [1; 2], and their grid structure is fabricated through laser processing [3], which, however, often results in problems including residual thermal stress, poor surface roughness, and sharp corners of the structure. Scholars have employed femtosecond laser processing to round the sharp corners and reduce the size of the melted zone on the surface; however, many problems remain [4; 5]. Postprocessing is thus required after laser processing to improve the quality of the stent surface and round the corners of the stent structure. Common postprocessing methods include sandblasting, chemical etching, and electropolishing [6]. Although these methods can produce high-quality surfaces and round corners, they require considerable work and time and have a high associated cost. In addition, the postprocessing operations may cause the loss of stent struts' width and shape accuracy [3; 4; 5; 6]. Moreover, because metal (stainless steel or nickel-titanium alloy) stents are not human body tissues, the body often rejects them, and the stents may have to be placed in the body permanently, making removal difficult. These factors all increase the risk of unpredictable body damage. Therefore, studies in which new stents have been developed have tended to use materials that are degradable by the body, such as PLA. PLA is a type of polymer material and is obtained from natural cellulose or starch. Because it is biodegradable and has satisfactory processing characteristics and mechanical properties [7], PLA is widely applied in packaging, vessels, and bioengineering devices such as bone screws, bone plates, surgical sutures, and carriers for drug release [8; 9; 10]. In the current industrial manufacturing, five-axis machine tools have been employed in the manufacturing of numerous products. The merits of these machines include that they overcome the limitation of cutter length, solve the problem of static cutting, are highly efficient at level processing, can process complex geometric shapes, reduce the number of times that workpiece installment is required, increase the size precision, and simplify the form of cutters [11]. Coordinate conversion formulas and computer-aided design or manufacturing tools can be employed to prevent interference during cutting and obtain the optimal cutting path [12; 13; 14]. The precision error of five-axis machine tools results from the static positioning error and dynamic tracking error. The static positioning error affects the processing precision between two points [15], whereas the dynamic tracking error affects the difference between the actual cutting path and instruction path. In practice, a linear variable differential transformer, which is a built-in retractable component for measuring displacement, can be used in the telescoping magnetic double ballbar testing to measure the error of circular motion of the feed axes and to compensate for the error [16]. For the eccentric error that refers to the cutter deviation from the rotation axis because of the geometric imperfection of the cutter, surface milling is performed using a ball end mill inclined at 45\({}^{\circ}\). The cusp height and pick feed on the surface are then measured and incorporated into the derived ball end mill radius compensation equation to obtain the correct outer diameter of the cutter [17]. Performing cutting at the microscale easily results in errors of the minimum cutting depth and material springback. For example, when aluminum is cut, the minimum cutting thickness and cutter radius are of the same order. If the cutting thickness is 0.2-0.3 times the cutter radius, the residual stress and roughness of the surface after processing are increased [18]. In addition, when the cutting depth is smaller than the critical cutting depth, material deformation may occur [19].