Effect of cutting parameters on hole defects while drilling Twill Reinforced Bio-composites

Abstract

Composites like CFRP and GFRP have been a popular alternative in several industries such as aerospace, automotive, energy, marine and consumer goods. However, these materials being non-recyclable, bio-composite materials are being investigated to explore areas where it can replace the conventional composites. One such alternative is Flax-Polylactic acid(PLA)-based bio-composite which is 100 % recyclable.
This study aims to investigate the effect of cutting parameters such as feed, cutting speed and type of drill on the defects produced while drilling 2 mm Flax-PLA based bio-composite materials. The study involves benchmarking 4 different drills and 72 combinations of cutting data for each of the drill. Further, the type of defects is classified and the defect areas are analysed against the used cutting data.
Results indicate that there are 7 different types of defects that can be observed while drilling bio-composites which are (1) Spiralled Crown Burrs, (2) Transient Burrs, (3) Uniform Cylindrical Burrs, (4) Fracture Burrs, (5) Exit Burrs with Drill Cap, (6) Inter-hole Longitudinal Burrs and (7) Uncut chips.
Feed rate plays the most significant role in determining the hole quality in this study. With the increase in feed per tooth from 5 µm/tooth to 10 µm/tooth, there is first a drastic reduction in defect area (mm2) owing to the relation between the cutting-edge radius of the tool and feed per tooth used which affects the rake angle, in turn affecting the chip thickness and defect area. Hence it is important to choose the starting feed per tooth (mm/rev) at least about 3 times the cutting-edge radius of the tool to avoid having extremely poor-quality holes.
The recommendation is to use the PCD CX-1 drill which produced the best hole qualities over a wide range of cutting data with minimum entry defect of just 2 mm2. The overall best quality holes were produced between fZ=60 µm/tooth to 90 µm/tooth and vc=100 m/min to 220 m/min with average defect area of 13.24 mm2. The lowest total defect area of 6.83 mm2 is produced at fZ=80 µm/tooth and vc=140 m/min.

Popular Abstract

Composites of carbon fibre and glass fibre have been a popular alternative to conventional metals in several industries such as aerospace, automotive, energy, marine and consumer goods. However, these materials being very difficult to recycle, bio-composite materials are being investigated to explore areas where it can replace the conventional composites. One such alternative is Flax-Polylactic acid (PLA)-based bio-composite which is 100 % recyclable.
The aim of this thesis work is to investigate the effect of cutting parameters such as cutting speed and feed rate on the defects developed while drilling 2 mm sheets of Flax/PLA bio-composites. This thesis is done in collaboration with SECO TOOLS AB, Drilling Centre based in Norrköping, Sweden.
This thesis involves drilling the bio-composite sheet using a milling machine at the university laboratory. Before starting to drill, a data set of machining parameters such as cutting speed and feed rate is decided. Since there was limited amount of literature on drilling this type of material online, it was decided to analyse a wide range of cutting speed and feed rates. In our case, 72 combinations of cutting data is chosen. 4 different drills were provided by SECO TOOLS and each drill was used to machine the selected cutting data.
While drilling, one can see several types of defects such a material being left uncut, of material being pushed out and formed extrusions on the surface etc. Therefore, once all the holes were drilled, a classification is made based on the type of defects seen while drilling bio-composites. Further, it is analysed how changing the cutting speed and feed affected the defects and provide with an optimal range of cutting data for each drill. To quantify this, the defect area is calculated for each hole using image processing in MATLAB software. Finally, the best cutting data is proposed that would give the best hole quality with least amount of defects seen while drilling bio-composites.
The importance of this study is that industries can use these results as their base data when drilling 2 mm sheets of bio-composites to understand the defects that can be seen while drilling 2 mm sheets of bio-composites. The proposed cutting data for drilling results in faster drilling and also with good quality. Hence it reduces the cost of the drilling process.

• author: Hindupur, Anirudh Kashyap
• supervisor: Andrew Hrechuk
• organization: Production and Materials Engineering
• course: MMTM05 20221
• year: 2022
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: drilling, PCD, cutting edge radius, defects, bio-composites, Flax-PLA
• report number: LUTMDN/(TMMV-5338)/1-97/2022
• language: English
• id: 9088480
• date added to LUP: 2022-06-14 11:51:07
• date last changed: 2022-06-14 11:51:07