The History of Acroloc

Acroloc Tool Change DemoThe ACROLOC Vertical Machining Center was designed by Jack Bayer of Bayer Industries, Phoenix, Arizona.

Its evolution pre-dates Numerical Control (NC) as the machine was initially introduced in the late 1960’s using a “pegboard” concept to program the machine.

As electronics technology advanced so did the ACROLOC and it evolved into a “CNC” Vertical Machining Center.

Machine construction followed industry standards with the exception of its unique tool holder and tool change design. The tool holder and changer design was a break from traditional taper type tool holders.  The ACROLOC tool holder is a compact tool change device that is built for quick change.  Its “chip to chip” tool time on average for the three inch tool is less than two seconds.  It is approximately four seconds on average for the large spindle models.


The ACROLOC premise is built on its fast tool changer which reduces production cycle times. This enables the user to be more competitive in its quotes, attain more jobs, and be more profitable. The tool change concept of the Acroloc is explained in the inset picture above that graphically depicts the statements below. The tool holder is held in the tool carousel which rotates the tool into position directly below the spindle.  As the spindle travels downward it passes thru the carousel locking the tool holder onto the spindle. The spindle begins rotation on its way to into the work.  When the tool completes its machining task the spindle retracts back thru the carousel depositing the tool holder into the carousel and the carousel rotates to the next tool position. The cycle is repeated for each tool thereafter until the program cycle is completed. The value equation is as follows:

  • For simplicity, assume the shop rate is $36.00 per hour which is one penny per second.
  • The ACROLOC “chip to chip” tool change speed is approximately 2 seconds or $.02.
  • Multiply the number of tools used during a machining cycle.
  • Calculate the cost per tool change.
  • Now calculate the cost of YOUR tool changer (a conventional drum or arm style equipped VMC is 10 to 15 seconds).
  • The average tool change time on conventional taper tool machinery is from 10 to 15 seconds (again that’s chip to chip tool change time). Conventional tool change devices typically must return to a “home position” to align the spindle with the gage line of the tool magazine or arm to effect the change. The spindle then must travel from the gage line back down to the work.  That distance is often 18 – 20 inches of travel or more. That up and down travel is lost “cutting” time adds cost to the piece part costs. A typical tool change cost on conventional taper tool equipment is $.15 cents per tool change versus $.02. That’s $.13 of LOST PROFIT from each tool change on every part cycle.


Sadly most U.S. machine tool builders have been driven out of business.  The loss of this vital part of U.S. industry occurred because of domestic over-regulation,  imbalanced U.S. Trade policies, foreign predatory business practices, and because foreign countries used multinational corporations and lobbyists who bought influence from ignorant U.S. bureaucrats, politicians, and trade representatives (i.e. these public servants sold out their country for personal gain).  Independent U.S. companies are among the most competitive in the world but they cannot compete when the COMPETITOR is subsidized by a foreign government.

In July of 1991 Bayer Industries succumbed to bankruptcy and was purchased by HURCO Manufacturing.  Hurco continued production of the ACROLOC until 1994 and then ceased its production.  Although the numbers of ACROLOC machines has diminished due to attrition (as have many U.S. companies) there are still several hundred in operation today.

Hurco transferred the parts and service responsibilities to McKenna Service Company in June of 2002.  McKenna Service Company has been directly involved as a dealer, and parts and service entity for over 30 years.  Our vast experience with the machines (dating back to the mid 1970’s) makes us well versed in every aspect of the equipment.  We continue to support the existing equipment base with a parts, tooling, manuals, technical support, CNC support and operational training.  We also rebuild ACROLOC machines when called upon.

Call us if tech support or parts are needed as we are always happy to assist in any way possible.