Dave Polito is my Star CNC guru.
He’s always been there when I’ve had questions, whether I was asking about a 1999 Star SA12, or a sweet SV38R located in Asia, or the ever flummoxing Siemens control on an ECAS-20.
Dave is the owner of Quality Machine Tool Services, the Star distributor for Illinois and southern Wisconsin. He has been servicing and selling Star Swiss screw machines for over 35 years. For much of his career he did technical service and applications. Quality Machine Tool Services started as strictly a service center and then in 2009 began selling Star machines.
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Star’s Distinction from other Swiss CNC Brands
Dave says that several top Swiss CNC screw machine producers make quality products, but Star’s service and the durability of its machines make it one of the best choices on the market. The machines have dovetail construction and their Fanuc control make them easy for operators of other machines with Fanuc control to adopt them. It’s not uncommon for 20-year-old Star machines to still be making good parts, so Star has continued to service all of the machines, and Star’s live tools can be used on all different generations of the brand.
A Refresher on Swiss Machining
Swiss style machines originated in the 1800s in Switzerland for the watch industry that needed to be able to produce parts with a long length to diameter ratio. Swiss style machines are able to produce precise long parts because the bar is supported by a guide bushing that prevents deflection. Swiss style machines are also known as sliding headstock machines because the headstock is what feeds the material through the guide bushing. Today’s Swiss technology is still important for making long parts, but it’s also significant because it enables users to produce complex complete parts. Typically, Swiss machines are used for runs of at least thousands. They aren’t nearly as fast as multi-spindles but are a lot faster than single spindle CNC lathes.
Machining with Ground Bar Stock vs. Unground Bar Stock
Swiss machining is generally associated with using bar stock that is ground to the desired tolerance of parts. Quality ground stock takes some of the variables away that could produce poor parts, so it’s usually advisable to use it when machining unattended.
However, Dave says only around 50% of Swiss work uses ground stock. Some improvements in technology such as Star’s rotary magic guide bushing have made it easier to machine cheaper unground stock. One of the benefits of the rotary magic guide bushing is that it creates air pressure to make sure it is not too loose nor too tight around the bar.
Machining with Guide Bushing (Swiss Style) vs Without Guide Bushing (Chucking Mode)
Using Swiss Style lathes without the guide bushing, also called chucking mode, has been growing more popular. Without a guide bushing, the machines cannot produce parts quite as long or precise, but the parts can still be high quality and machined complete. Using no guide bushing enables smaller bar remnants when a bar has been used up because the bar doesn’t have to travel over the added space of the guide bushing.
Turret Swiss Lathes vs. Gang Style
Turret style Swiss Lathes, often used for medical work can produce far more complex parts than gang style machines because they can hold 50 live tools at a time, while a gang style machine holds only a fraction of that. People also like the turret style machines because with so many live tools on the turret they can limit setup changeovers by producing families of parts. However, turret style machines have larger footprints than gang style machines and much larger price tags. An entry level 5-axis gang style machine starts around $100,000 without a bar feed. A 6-axis SR gang style machine starts at around $200,000 without bar feed. Turret style machines can cost more than $500,000 depending on how they are tooled up.
Current Market for CNC Swiss
Dave says Star still has a backlog of orders for its machines. A popular model like an SR20 will take about 6-8 weeks to arrive at a customer. Earlier in the year it might have taken several months to get a machine. The lead time has been reduced by supply chain bottlenecks lessening.
Dave says customers he talks to still seem confident they will continue to get a lot of Swiss work going forward, despite the nervousness in the current economy.
Star sells more machines to China than anywhere else in the world. Dave says he has heard that Chinese companies buy the same number of machines in one month that U.S. companies might buy in a year.
Question: What is the most lucrative part you have made on a Swiss screw machine?
This article was originally posted on https://todaysmachiningworld.com/star-cnc-swiss-guru-with-dave-polito/