STAMA Unveils New Concept in Multi-Spindle Machining

"The '2 Plus 4' principle has represented the most economical and efficient means of multi-spindle machining in manufacturing," said a STAMA spokesperson. "STAMA has implemented this principle, with two spindles and four clamped workpieces, in hundreds of existing projects worldwide, resulting in reduced cost per part scenarios for its customers. In today's highly competitive market, however, STAMA has recently conducted discussions with its customers concerning greater factory floor utilization and 'non-productive' capacity, leading to the question: are more than two spindles-perhaps even four-for the simultaneous machining of workpieces, economically more reasonable? This challenge has sparked an interesting development at STAMA, the 4-spindle TWIN2 concept that is now being introduced to the world market for multi-spindle machining applications.

"In answering this two vs. four question, a shop must first verify which productivity upsides will be realized by this concept. Contrary to 'logical' expectations, the 4-spindle solution with four clamped workpieces doesn't result in double the output, compared to a 2-spindle production with four clamped workpieces. In the relationship between the primary machining time and the overall cycle time of the process, the actual output will usually increase by 60 to 70 percent by adding two more spindles. Individual exceptions with short time-consuming machining operations can reflect an increase of more then 80 percent," according to STAMA research.

"While twin spindle machining needs to double the capacity of the tool magazine, the 4-spindle solution requires a tool magazine to handle four times as many tools. The STAMA MC 531/TWIN is equipped with 56 tool places in the standard version, for example, with options for magazines up to 120 tools.

"One major key in 4-spindle machining, with short tool-to-part contact times, is the load and unload sequences of the workpieces. In such cases, as long as the machine isn't equipped with a quick automatic loading/unloading system, pendulum machining is more advisable. This ensures parallel machining time while loading new workpieces. Time for loading and unloading can then be as long as the actual cycle time of the machine. This will also result in less time when the operator is interacting with the machine, thereby allowing the operator to run multiple stations in a work cell setup, while keeping a constant touch time protocol on each machine," said the spokesperson.

"Under these conditions, for many workpieces studied by STAMA and its customers, the '4 Plus 4' solution can result in major cost per part reduction. With over 25 years' experience in TWIN spindle technology, the simplicity of a common Z-headstock for twin spindles from STAMA is well-accepted and proven technology worldwide. The simplicity of this system is also used throughout this new TWIN technology. Incorporating a state-of-the-art tool presetter, even single spindle manufacturing challenges with high accuracy demands can be realized with multi-spindle technology. The outstanding productivity and high workpiece quality achievable are the benchmarks by which STAMA TWIN spindle centers are known. The expansion to this 4-spindle TWIN2 machining center technology is the logical consequence of the company's latest research and machine development strategies.

"Already in use at a STAMA customer in one of the BRIC markets is a new four-spindle TWIN2 machining center, currently doing ABS housing manufacturing and connecting rod machining. This success for STAMA evidences the simplicity and practical application of the company's highly productive manufacturing equipment," said the spokesperson.

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