burr

(redirected from burs)
Also found in: Dictionary, Thesaurus, Medical, Financial, Acronyms, Idioms, Wikipedia.

burr

1, bur
1. a washer fitting around the end of a rivet
2. a blank punched out of sheet metal

burr

2, buhr, bur
1. short for buhrstone
2. a mass of hard siliceous rock surrounded by softer rock
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Burr

 

(also called flash), a projection on the surface of a product that is being worked; it forms as a result of the extrusion of material into the gap along the joint of a tool (a die or a pair of rollers) or because of imperfect cutting of the billet. When metal is worked using other methods, burrs are formed only if the production process has not been adjusted properly or if a worn tool is used.


Burr

 

in woody trees, a thickening or growth on the trunks, branches, or roots. Burrs result from the local thickening of tissues, apparently in response to irritation or damage to cambium cells and dormant buds by fungi, frost, fire, or mechanical injuries (blows, slashes). According to the external appearance and to the structure of the fibers, two types of burrs are distinguished: those with smooth surfaces and slightly wavy wood and those with uneven surfaces and knotty wood (burls). The former type develops on the trunks of all varieties of trees; on pines and firs such burrs have wavy and relatively broad annual rings and consist of short thick-walled tracheids with curved or separated ends and of numerous large heartwood rays. The wood of burrs is much denser and harder than the ordinary trunk wood. Depending on dimensions and texture, burr wood may be used for producing structural ornament or for small household and artistic objects.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

burr

[bər]
(botany)
A rough or prickly envelope on a fruit.
A fruit so characterized.
(metallurgy)
A thin, ragged fin left on the edge of a piece of metal by a cutting or punching tool.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

burr

1. A waste brick from the kiln which has been partially fused.
2. A batch of bricks fused together.
3. A rough or sharp edge left on metal by a cutting tool.
4. Same as burl, 1.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

burr

A type of metal damage in which the sharp, rough edge of a piece of metal is left when the metal is sheared, punched, or drilled. This type of damage is more common in case compressor blades.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
References in periodicals archive ?
The primary reason was to confirm the efficacy of the dye to stain only contaminated surfaces, and, secondly, to assess the sterility of brand new burs. We found that only one unsterilized brand-new bur in the negative control group showed contamination that can be due to handling error.
Manual cleaning, is simple and cost-effective but can potentially serve as a source of contamination due to the aerosols produced during the process.12,13 Manual scrubbing also produce unpredictable results, as it is very operator-sensitive.6 In our study, 77.14% dental burs in Group-1 demonstrated contamination.
Ultrasonic cleaning has been found to be effective in removing saliva and dried blood from the dental instruments and increases safety of dental personnel during handling of instruments.24 In the present study, 82.85% burs in Group-2 showed contamination.
Enzymatic agents help to digest organic debris, including bacteria due to presence of amylases, lipases and proteases, but their use is operator-dependent and if manufacturer's guidelines are not exactly followed regarding dilution of enzyme solution, its immersion time, reuse of solution greatly affects the cleaning efficacy and might lead to recontamination of dental instruments.6 In the present study, the burs in group-3 were treated with a combination of manual cleaning followed by immersion in the enzyme solution.
The burs in the test group-4 were subjected to a combination of pre-cleaning methods (manual + ultrasonic + enzyme) and yet 68% diamond dental burs exhibited contamination.
Our results suggest that current methods of pre-cleaning of dental burs might be insufficient to ensure complete cleaning of contaminants.
- Mean numbers of propagules from 30,000 burs and legumes fed passed per steer during each of four 24-h periods postfeeding for the propagule-type by sampling-period interaction, and totals Period after feeding (h) Type 0-24 24-48 48-72 72-96 Total (propagules) Burs 153 Aa(a) 483 Aa 272 Aa 89 Aa 998 a Caryopses 148 Aa 492 Aa 337 Aa 138 Aa 1114 a Legumes 2830 Bb 5220 Cb 977 Aa 199 Aa 9226 b a Means within rows followed by the same uppercase letter, and means within columns followed by the same lowercase letter, are not significantly different at the 0.05 level as determined by paired comparisons Both sets of results are reasonable given the methodologies of the respective studies.
Most of the burs in our study were destroyed during passage, and relatively few intact caryopses survived passage.
If most burs and caryopses are destroyed when consumed by cattle on forage diets, this would initially appear to argue against buffalograss fitting the FF hypothesis, specifically expected trait 7: "Seeds are sufficiently small, tough, hard, and inconspicuous enough to escape the molar mill and spitting response of a large mammal," (Janzen, 1984).
Percentage germination of burs was negligible in all experiments, but percentage germination of caryopses was significantly higher than for burs recovered from the feces at some time periods (Table 3).
It should be noted, however, that the burs were kept in the germination chamber after the 28-day run.
Mean time to complete germination was not different for burs and caryopses in the control treatment, but was considerably less (P [less than] 0.05) for caryopses than for burs in all fed treatments (Table 4).