Featured Research

from universities, journals, and other organizations

Manufacturing: Chip-free ceramics

Date:
February 13, 2013
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
Rethinking the process used to machine industrially important ceramics could reduce damaging cracks and chips.

Rethinking the process used to machine industrially important ceramics could reduce damaging cracks and chip.

Ceramics are hard, chemically inert and can withstand high temperatures. These attributes make them ideal structural components in engines, high-performance disk brakes and medical implants. However, as ceramics are also brittle, using conventional tools -- such as drills -- to machine them is difficult. Instead, manufacturers rely on ultrasonic machining, in which a 'hammer' rapidly vibrates up and down. This process pushes slurry, which contains fine and abrasive grit, into the material and causes chipping.

Research by G.C. Lim and co-workers at the A*STAR Institute of Manufacturing Technology, Singapore, has now improved understanding of how this abrading process creates cracks in a ceramic, making it less durable for applications1. The team's findings could inspire new approaches to machining ceramics, a key element in Singapore's rapidly growing manufacturing sector.

Ultrasonic machining is known to leave cracks at the entrance and exit of a drilled hole, and a rough surface within the hole (see image). Often, these defects are visible only under a microscope; nonetheless, they make the hole and surrounding material more susceptible to wear and tear. "Imperfections act as initiating locations, where cracks and fractures occur and propagate more easily than other places, resulting in early failure of the component," says Lim.

The researchers studied crack formation by drilling holes of between 0.7 and 3.0 millimeters in diameter into plates made of 3 industrially important ceramics: silicon carbide, zirconia and alumina. They recorded images of the cracks and chips along the inner sides of the holes with a microscope and then used diagrams to model the way force is transferred from the hammering tool to the grit, and from the grit into the ceramic.

Lim and his colleagues found that as the grit removes material -- by making tiny pits or rubbing against the walls -- it creates cracks, which can be up to four times longer than the grit particles and extend out radially from the hole. The team concluded that these cracks are inherent to the way ultrasonic machining works, which means the number of cracks can be reduced by using smaller grit particles but never entirely eliminated.

Lim says they are now in a better position to optimize the drilling process. Since the smallest grit particles yield the smoothest holes but make drilling take longer, Lim recommends a two-step process: quickly drill a slightly smaller hole than needed with a large grit size, and then use a smaller grit size to make the final hole with a smooth finish.

The A*STAR affiliated researchers contributing to this research are from the Singapore Institute of Manufacturing Technology


Story Source:

The above story is based on materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Materials may be edited for content and length.


Journal Reference:

  1. Chandra Nath, G.C. Lim, H.Y. Zheng. Influence of the material removal mechanisms on hole integrity in ultrasonic machining of structural ceramics. Ultrasonics, 2012; 52 (5): 605 DOI: 10.1016/j.ultras.2011.12.007

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Manufacturing: Chip-free ceramics." ScienceDaily. ScienceDaily, 13 February 2013. <www.sciencedaily.com/releases/2013/02/130213173041.htm>.
The Agency for Science, Technology and Research (A*STAR). (2013, February 13). Manufacturing: Chip-free ceramics. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2013/02/130213173041.htm
The Agency for Science, Technology and Research (A*STAR). "Manufacturing: Chip-free ceramics." ScienceDaily. www.sciencedaily.com/releases/2013/02/130213173041.htm (accessed July 29, 2014).

Share This




More Matter & Energy News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Newsy (July 28, 2014) Stanford University published its findings for a "pure" lithium ion battery that could have our everyday devices and electric cars running longer. Video provided by Newsy
Powered by NewsLook.com
The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Shipping Crates Get New 'lease' On Life

Shipping Crates Get New 'lease' On Life

Reuters - Business Video Online (July 25, 2014) Shipping containers have been piling up as America imports more than it exports. Some university students in Washington D.C. are set to get a first-hand lesson in recycling. Their housing is being built using refashioned shipping containers. Lily Jamali reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins