Session: 17-01-01: Research Posters

Paper Number: 148696

148696 - Effects of the Cutting Process Parameters on the Quality of 5h Biaxial Woven Carbon-Fiber Dry Fabric Patterns 

The RTM (Resin Transfer Molding) process, one of the out of autoclave (OAA) composite manufacturing processes, typically begins with cutting dry fabrics into geometric patterns to develop preforms. Dry carbon fabrics should be cut accurately so that the cut fabric patterns conform precisely to the mold's geometry. Although various technologies such as die cutting, laser cutting, and abrasive waterjet cutting have been studied for dry carbon fiber fabrics, one of the most widely used technologies in composite industries has been drag knife cutting performed on the dry carbon fiber fabrics laid over a CNC table, which is a focus of this study. This experimental study aims to investigate three different tungsten carbide cutters used in the straight cutting of 5 harness satin (5H) biaxial woven fabric made of standard modulus carbon fibers, as well as the effects of sacrificial sublayers during the cutting process, with an emphasis on the quality of the fabric patterns being cut. The three cutters, including a traditional drag knife, an ultrasonic cutter, and a rotary cutter, were used in the cutting of 25.4 mm or 1-inch wide patterns in a CNC milling center. A single piece of carbon fiber fabric was placed in a vacuum plate with a pressure ranging from 71kPa to 85kPa for five cutting operations in each experimental condition. The first set of experiments consisted of four cutting process input parameters, including a blade angle relative to the cutting surface given as 15° and 45° respectively, fiber orientation relative to the tool path given as 0°/90° and 45°/135° given the biaxial nature of the material, feed rate of the tool given as 2.5m/min, 6.3m/min, and 10.2m/min, while the last was only considered for the ultrasonic cutting implement, which was a variation in the blades amplitude (0% to 50%) while operating at a fixed frequency of 1440Hz. The results of the drag knife and the ultrasonic cutter show that the changes in the fiber orientation had minimal effect on the average feed force. However, the average thrust force shows a larger change, increasing from 3.10N at 0°/90° to 4.33N at 45°/135°, suggesting that the cutter requires interacting with all individual fibers when cutting the 45°/135° fibers. In addition to fiber orientations, the drag cutter’s angle against the feed direction presented a clear impact on cutting forces. The average thrust force was 5.58N at the 15° cut angle, while it was reduced by more than half to 2.29N at the 45° cut angle. Using an optical microscope, the four patterns of each experimental condition were measured for width from edge to edge to evaluate precision and accuracy. The rotary cutter outperformed the other two implements, resulting in an average width ranging from 25.5mm to 25.6mm, offering the lowest dimensional errors of 0.1 mm to 0.2 mm. The combination of high thrust force and low feed force resulting from the rotary cutter at the feed condition of 10 m/min resulted in the best overall cutting performance. In the second set of experiments, the experimental inputs were four sacrificial plates with a range of hardness, consisting of polycarbonate and silicone, ranging from 40A to 60A in hardness (Shore-A scale), with a primary interest of assessing the effect of the sacrificial plate’s hardness on cutting quality when using the rotary cutter. The soft silicone (40A) resulted in unsuccessful cutting due to the fabric’s large deformation in the sublayer, hindering the knife’s engagement. Although it was observed that both the thrust and feed forces decreased as the silicone hardness increased potential due to reduced workpiece mobility during the cutting operations, the medium silicone (50A) sublayer produced the outperforming results in terms of pattern width accuracy over other sublayers. The experimental condition with the medium silicone sublayer using the rotary cutter, resulting in an oversized width ranging from 0.17 mm to 0.31mm on average and a standard deviation of 0.048 mm for the true pattern width of 25.4 mm, meets a desired tolerance of +/- 1 mm from an aerospace manufacturer.

Presenting Author: Chris Miskell Washington State University Vancouver

Presenting Author Biography: Chris Miskell is currently a graduate student with Washington State University Vancouver, working towards a master in mechanical engineering degree. His primary focus or interest is working in the area of materials science and manufacturing, with an emphasis on the aerospace sector, primarily in researching composites manufacturing and their applications.

Authors:

Chris Miskell Washington State University Vancouver
Dr. Dave Kim Washington State University Vancouver