Determination of Processing Precision of Hole in Industrial Plastic Materials

Abstract

The precision of the thread processed by tapping is closely related to the precision of the pre-drilling of the blank. Currently, the technologies for processing threads with the tap in the case of metals are well established. In this sense, there are tables and clear recommendations about the tool pairs—helical drill-tap, depending on the size of the thread, but in the case of plastics, no correlations or recommendations have been found. A well-known aspect concerns the fact that the hole made in plastics is obtained with a smaller diameter than the diameter of the drill bit used. To determine the differences between the drill bit and the diameter of the resulting hole, and its precision on different types of plastic materials, experimental research was started. At the same time, the tolerance of the resulting hole was checked and the influence of the cutting regime on the processing precision was studied. During the experiments, plastic materials often used in the aeronautical and car-building industries were used: POM-C, PA6, PEHD1000, Sika Block 700, Sika Block 960, and Sika Block 980. Following the experiments, differences in the diameter of the holes processed were found according to the plastic mass of even 0.3 mm, which is 4.4% of the diameter of the hole. Based on the experimental results and the design of the experiment, recommendations could be made about the diameter of the drill to use to obtain the desired diameter of the hole after processing.

Influence of Machining Parameters on the Dimensional Accuracy of Drilled Holes in Engineering Plastics

“…The quality of the holes was checked using a coordinate measuring machine (CMM) to assess the diameter and cylindricity at 2 planes × 10 points along each hole ([ 36 ], Figure 4). The volumetric accuracy of the machine is 1.8 µm + L/400 (L is the measured length) and the repeatability is 1.7 µm.…”

“…The volumetric accuracy of the machine is 1.8 µm + L/400 (L is the measured length) and the repeatability is 1.7 µm. The measurement method involves evaluating the diameter and cylindricity by probing the surface on two planes and, in each plane, 10 contact points around the circumference of the hole to detect variations ([ 36 ], Figure 4).…”

“…Another issue worth mentioning in relation to the literature survey conducted concerns advanced measurement and analysis techniques. In this direction, studies by [ 28 , 29 ] have been identified that follow advanced measuring techniques in polymer machining [ 30 , 31 , 32 , 33 ], dealing with the issue of coordinate measuring machines (CMM) for polymers, while [ 34 , 35 ] address the topic of artificial vision systems for machined parts, and [ 36 , 37 , 38 , 39 , 40 ] discuss precision and accuracy in polymer drilling. All of these papers explore state-of-the-art equipment and use software in the accurate measurement of machined-part features, with a focus on coordinate measuring machines and machine vision systems.…”

“…Ravai-Nagy et al [ 36 ] determined the accuracy of hole processing in industrial plastics and demonstrated that optimizing the cutting speed and feed rate can reduce deviations and improve cylindricity.…”

Effect of Drilling Parameters and Tool Geometry on the Thrust Force and Surface Roughness of Aerospace Grade Laminate Composites

“…Various common methods are employed to mitigate this problem. These include the manufacture of drills with varied shapes and quality levels, adjusting cutting parameters for optimization, and implementing peck drilling techniques [ 19 , 20 , 21 , 22 , 23 ].…”