TM 9-2610-200-14 E-4 APPENDIX E: GLOSSARY (Con't) Lug Tearing      Rupture of the lug, sometimes resulting in its removal, caused by violent   operation or mechanical interference . Mandrel   A curved support inserted in a tire to prevent the casing from collapsing   while building a repair. Moisture Blows Ply separations caused by the presence of moisture in the casing that,   when subjected to heat, becomes steam and expands. Mold    Equipment in which the new tread is cured to the worn tire. Mold   includes the steam chamber, matrix, and adjusting devices. Optimum Cure   That state of cure at which the rubber compound exhibits the most   satisfactory physical properties. Usually expressed in minutes curing time   at a specified temperature. Overbuff   Removal of too much material by buffing. Buffing an area too large for reinforcement patch or die size of rubber to be used . Overcure Vulcanizing longer than necessary .Can result in the deterioration of   certain physical properties. Ozone Active form of oxygen, usually caused by static electricity, that is very   harmful to rubber. Causes checking and cracking often attributed to aging or weathering. Ozone Resistant   A formulation of rubber resistant to the cracking effect of ozone in the   atmosphere. Although the ozone resistance of natural rubber is poor, it can be improved by compounding with anti-ozone chemicals and waxes. Pinholes   Minute circular voids in cured or uncured rubber. Plug     A piece of new rubber vulcanized into tread or sidewall injury. Ply A layer of rubber coated parallel cores, several of which, laid one across   the other, make up the casing of the tire. Ply Separation   A parting of rubber compound between adjacent plies. Potentiometer    A multivoltmeter calibrated to sense temperature in a desired range   (usually direct reading). Premature Vulcanization   Uncontrolled curing or setup (loss of flow qualities) in material before final cure.   Pyrometer   An instrument to measure temperatures. usually by the generation of   electric current by a thermocouple when acted on by direct heat.   Commonly used to measure surface mold temperatures or, if a   penetrating needle is used, tread rubber temperatures.