COMBINING FUSED DEPOSITION MODELLING WITH ABRASIVE MILLING TO ATTAIN HIGHER DIMENSIONAL ACCURACY AND BETTER SURFACE FINISH ON THE FINISHED PRODUCT

Abstract

ABSTRACT: Currently, two manufacturing methods, namely CNC (Computer Numerical Control) machining and rapid prototyping (RP), are widely used to produce final products and prototypes. Both the processes have their own advantages. CNC machining such as milling and grinding (subtractive method) can fabricate parts with higher precision and accuracy. On the other hand, RP (additive method), can manufacture parts with complicated 3-D (three dimensional) features, which ensures effective material usage. However, RP produced parts lack accuracy and smooth surface finish. In this research, we are aiming to achieve on-machine mechanical post-processing of 3-D printed (using Fused Deposition Modelling, a kind of RP process) parts to achieve higher dimensional accuracy and better surface roughness. To achieve the goal, we developed a new hybrid system to assimilate both of these processes. There are, however, two vital considerations needed to be taken into account for integrating the two processes. The first concern is the integration of dissimilar control systems for two processes and the second aspect is maintaining the tools’ (milling spindle and the heat extruder) setup accuracy during the changeover step. The developed hybrid machine has been tested with experimentations and the result showed that the dimensional accuracy was improved by 71% to 99% when the FDM part was compared with the final part after abrasive milling operation. At the same time, average surface roughness (Ra) was improved up to 91.3%. Further, we found that low layer thickness improves the product quality. The proposed system could push the conventional FDM system to the next level to attain better quality of final products. ABSTRAK: Dua kaedah terkini proses pembuatan, dinamakan mesin Kawalan Komputer Bernombor (CNC) dan prototaip langsung (RP) telah digunakan secara meluas bagi menghasilkan produk dan prototaip. Kedua-dua proses mempunyai keistimewaan tersendiri. Mesin CNC seperti mesin penghasil permukaan dan mesin penebuk lubang (melalui kaedah pengurangan) dapat menghasilkan sesuatu bahagian dengan ketepatan tinggi. Pada sudut lain, RP (melalui kaedah penambahan), dapat menghasilkan bahagian dengan kaedah 3D (tiga dimensi) yang rumit tetapi berkesan dalam memaksimakan penggunaan material. Walau bagaimanapun, penghasilan bahagian melalui kaedah RP mempunyai kekurangan pada ketepatan dan kekurangan pada kekemasan permukaan akhir. Kajian ini bertujuan meraih ketepatan dimensi yang lebih tinggi dan kekemasan permukaan yang lebih bagus pada proses terakhir pada bahagian cetakan mesin mekanikal 3D (menggunakan Model Deposit Fuse iaitu salah satu proses RP). Bagi mencapai tujuan ini, kami menghasilkan sistem hibrid terbaru untuk mengasimulasi kedua-dua proses. Walau bagaimanapun, terdapat dua perkara penting perlu diambil kira untuk diintegrasi bersama kedua-dua proses. Penilaian pertama adalah pada sistem kawalan tidak serupa, dan kedua pada aspek pengekalan alat (gelendung pemutar dan kepanasan pembentuk) ketepatan penyediaan semasa peringkat perubahan. Mesin hibrid yang dicipta telah diuji melalui eksperimentasi dan keputusan menunjukkan ketepatan dimensi telah bertambah daripada 71% kepada 99% semasa bahagian FDM dibandingkan dengan bahagian akhir selepas operasi putaran kasar. Pada masa sama, purata permukaan kasar (Ra) telah bertambah kepada 91.3%. Kami juga mendapati ketebalan lapisan bawah telah menambah baik kualiti produk. Sistem yang dicadangkan dapat mengubah sistem FDM konvensional kepada peringkat lebih tinggi bagi memperolehi kualiti terbaik pada produk akhir.

Keywords

• fused deposition modelling
• abrasive milling
• hybrid system
• fdm
• rapid prototyping