Definition
Junk Mill — A junk mill is a fishing tool dressed with hard cutting material such as tungsten carbide that grinds up junk, debris, or an unrecoverable fish downhole into small pieces that can be circulated out or caught in a junk basket.
Also known as: junk mill, mill, milling tool
What a junk mill does
When a fish cannot be caught and pulled — because it is broken, collapsed, or is simply loose metal junk on bottom — a junk mill is used to destroy it in place. The mill’s face is dressed with crushed tungsten carbide or other hard facing that grinds the obstruction into fine cuttings and fragments as it rotates under weight. The debris is then carried up by circulation or collected in a junk basket run above or below the mill.
Types of mills
Common variants include flat-bottom junk mills for milling on hard junk, taper mills for dressing or reopening a restricted top, pilot mills that mill over a stub while guiding on its bore, and section mills that cut casing. Adequate weight, controlled rotary speed, and good circulation are essential to mill efficiently without glazing or damaging the cutting structure.
Why it matters for rentals
Mills are consumed by the cutting they do and must be sized to the hole and junk, so operators typically rent them per job.
Our fishing tools include junk, taper, and pilot mills for rental — contact us to select a mill for your junk and hole size.