Wear of Diamond-impregnated Bit in Drilling Engineering Ceramic
This paper describes experimental results using a scanning electron microscope (SEM) to observe the face of diamond-impregnated bit after its drilling engineering ceramic. Wear patterns and mechanisms were analyzed. The results show that several diamond wear patterns are found in the bit face including complete crystal shape, micro fragmentation, extensive fragmentation, whole fragmentation, wearing flat and particle shattered, bond abrasion mainly is in the form of shifting sand pattern, alternating thermal stress and mechanical stress are the main reasons which lead to the diamond wear, extrusion force, friction as well as abrasive debris erosion result in the shifting sand pattern of the bond.
Performances of Diamond Impregnated Bit in Hole Drilling of Engineering Ceramics
According to the mechanical characteristics of engineering ceramics,the special diamond impregnated bits are developed for hole drilling.The cutting performances of the bits are analyzed from the following aspects,such as bit wear,working life,machining efficiency and machining quality.The results show that: the whole bit wear process can be divided into three phases;the regularity of the machining time per hole with the number of holes machined is close to a periodic variation;higher machining efficiency or working life can be obtained when the drilling pressure and the wall thickness of the bit are advisable.Aiming at the drilling defects in engineering ceramics,drilling with compressive pre-stress is proposed.Experimental results show that the bit is suitable for the drilling of engineering ceramics.Research achievements provide technical bases for the application of diamond impregnated bits in hole drilling of engineering ceramics.
Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 ? 1 Rib Cotton Knitted Fabrics
This study investigates the impact of yarn count and stitch length of 100% cotton knitted fabrics. 1 × 1 ribs structured fabrics were used in this research work. The stitch length 2.50 mm, 2.52 mm, 2.60 mm, 2.70 mm, 2.80 mm and 2.96 mm were used of the yarn count of 26Ne, 28Ne and 36Ne. The areal densities of the grey fabrics were in various amounts. The impacts of yarn count and stitch length were measured concerning pilling resistance, abrasion resistance, and shrinkage and tightness factor. The result showed that the fabric pilling grade decreased while number of cycle increased. Abrasion resistance decreased but length wise shrinkage increased despite the fact that the stitch length increased. The results also exposed that the tightness factor of the fabric increased with the increase of the stitch length in both dyeing and washing state and finished state compared to grey state for the yarn count 26Ne and homogeneous result not found for yarn count 28Ne and 36 Ne. Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 × 1 Rib Cotton Knitted Fabrics