BUCHER Emhart Glass removes the bottleneck in parting off

END USER: Emhart Glass Manufacturing Inc., (607) 734-3671, www.emhartglass.com.
CHALLENGE: Increase productivity when parting off a component.
SOLUTION: A new parting and grooving tool that practically tripled machining parameters.
SOLUTION PROVIDER: Sandvik Coromant Co., (800) SANDVIK, www.sandvik.coromant.com/us.

Glass containers and bottles are so ubiquitous that most people have used containers that were formed and inspected on a BUCHER Emhart Glass machine, according to the company. Providing glass containers for more than a century, Bucher Emhart Glass says it developed the industry-standard Individual Section (IS) machine, a glass container forming device. This machine has a bank of five to 20 identical sections, each of which contains a complete set of mechanisms for making different-sized formed glass containers—most destined for the medical, scientific, or food and beverage industries.

In glass manufacturing, inspection and defect analysis is a critical step. To ensure Bucher Emhart Glass continued to provide top quality glass containers, the company purchased Powers Manufacturing, Elmira, N.Y., in 1982. Powers was a supplier of cold-end inspection equipment.

The Elmira outpost of BUCHER Emhart Glass, which still designs, machines, assembles and ships complex inspection machines, employs about 140 people, with a machine shop and assembly all under one roof. The machine shop portion of the facility occupies roughly 12,000 sq. ft., with 25 employees covering two shifts.

Images courtesy Maria Strinni for Sandvik Coromant

Emhart Glass’ empty bottle inspection system uses a camera to look through the top of the bottle and take an image of the bottom. That image is used to detect flaws. The machined components in this parting-off application are used in a device that rotates the bottle within the machine during testing.

The shop has seven vertical machines, two horizontals, three 3-axis-lathes and a 7-axis-lathe. The brand mix includes a Mazak mill and turning machine, three Hardinge lathes, two Haas machines, one Komo, and a Bridgeport vertical. Primary materials include Ledloy 12L14, which tends to be softer and easier machine than other materials, and aluminum, bronze and stainless steel, which tend to be tougher.
The workflow at the Emhart machine shop is punctuated by numerous short-run jobs. To limit downtime, this schedule requires operator flexibility as frequent changeovers put increased pressure on the machines and tooling to run as quickly as possible. These short-run jobs require optimal cutting speeds and long tool life in order for the shop to stay productive.

“We’ve been using Sandvik Coromant tooling since the mid-1990s, mostly for milling and turning,” said David Turk, manufacturing CNC engineer at Emhart Glass. “Sandvik Coromant is our dominant insert and toolholder supplier. We have a few others, but they account for probably 80 to 85 percent of our indexable carbide. We have a good relationship with our local tool supplier, One Time Tool, and they suggested we try Sandvik Coromant—we did and we’ve been using them ever since.”

Although Turk was already using Sandvik Coromant tooling for other operations, he was not convinced to change the current operation for parting-off components on a lathe. Sticking with a process and a product he has used for years, he kept an eye out for products offering significant improvement, but nothing he tested was that much better. Parting-off is not a rarely-used operation by Emhart; it is required for several components.

As it’s frequently the final stage of the machining process, parting-off is a crucial step. Between machine setups, programming, and time already spent making chips, operators and machines have invested quite a bit into machining the component by the time parting-off is considered. Parts have already been turned, tapped, drilled, grooved and finished prior to parting-off. Scrapping a part after such an investment in time and machine capacity is simply not an option at this point. So, sticking with the process that Turk and others at Emhart believed to be the safest bet was what they were going to do unless something could radically change their productivity levels.

Warranting a switch
“We had tried different inserts, different suppliers, even some inserts from Sandvik Coromant—we just didn’t see enough results to warrant any changes,” Turk said. “Because we do a lot of short-run jobs, and there already is a lot of setting up and making programming changes, we wanted to see something where we could get a lot of bang for our buck upon making the switch. Over the years we saw some marginal increases in speed and efficiency with other inserts and tooling, but not enough to push our hand to make a change.”

But even though Turk hadn’t been sufficiently wowed by any other parting-off tooling on the market, the operator, Tom Waite, again asked Turk to keep an eye out for new tooling for the parting-off operation in the fall of 2013. Meanwhile, Jim Pappas, sales engineer at Sandvik Coromant, had just completed training on the company’s new CoroCut QD parting and grooving tool. The timing was serendipitous for Pappas to give Turk a ring.

Component being machined here is the one used in bottle rotation (as in the previous image). The material is 3½”-dia. 12L14 steel. With CoroCut QD, EmhartGlass machines the components at 600 sfm and 0.007″/rev. With the previous tool, Emhart had to run at 220 sfm and 0.002″/rev.

Coolant coming out of the tool tip, at the cutting surface, which is a departure from the previous setup, where coolant was delivered from above.

Tom Waite measures the snap ring groove diameter in the machined component.

Turk uses a height gage to judge thickness of the parted-off component to the side diameter. The new CoroCut QD cuts as accurately as or more accurately than the previous tool, while cutting much faster.