Cutting Tools: Milling better moulds
- November 1, 2015
The Solution: High feed milling tools
Ontario mould shop improves productivity using new high feed milling tools
The tooling story continues at Build-A-Mold in Windsor, ON. After much success with progressive high feed milling cutter technology a while back, the mouldmaking shop has spread the advanced-tooling “love” so to speak to several new machine tools and other processes throughout its operations. And as a result, production efficiency further increased, mould production costs dropped and all previously outsourced work is back in-house.
Build-A-Mold’s first foray into advanced tooling involved its older boring mills and gantry style mills doing 2D roughing operations. In that instance, Build-A-Mold doubled, and in some cases even tripled, metal removal rates with the tooling switch while also gaining significant increases in tool life. But most recently, however, the shop experienced these same benefits and many others in its 3D roughing, hard milling and reaming operations along with its sinker EDM electrode machining processes.
Rob Caixeiro, mouldmaking manager at Build-A-Mold, and Joe Hindi, the company’s CNC supervisor, spearheaded the first re-tooling project. That was about three years ago and shortly after Caixeiro and Hindi joined the Build-A-Mold team and took the helm of what they described as a tenured and very experienced mould shop.
So for its most recent re-toolings, Caixeiro and Hindi relied on their highly skilled and motivated staff to drive and guide the projects. Steven Horvath, computer-aided machine operator, led the hardmilling project, and Paul Van Snick, CNC EDM lead, the EDM electrode machining one.
Jeff Bailey, boring mill technician, headed up the reaming projects, while Keith Andreoff spear headed the roughing ones. Bailey and fellow boring mill team members Paul Pinsonneault, Joe Scalia and Curt Sexton were involved with the initial high feed milling project. And since those successful milling cutters came from Seco Tools, Caixeiro and Hindi turned to Seco again for tooling and application support.
For two new Makino A61NX horizontal machining centre (HMC) cells, Build-A-Mold equipped them with Seco’s Jabro ballnose and flat solid carbide end mills and heat shrink holders to boost tool life for hard milling operations. The shop’s previous tools lasted for only one program pass, while the Jabro cutters provide three passes, which is typically enough to complete a part.
The cells process mould components (lifters and slides) as well as forming board components in a variety of materials, including D2, M2 and others up to 62 Rc in hardness. The cells run 24/7, and part sizes vary from 50.8 mm (2 in.) square up to 508 x 762 mm (20 x 30 in.). Hard milling eliminates a step in the process to reduce cycle time and help lower part product costs.
“Each hard milling pass can last up to 1.5 hours and typically takes 0.020 in. depths of cut per pass. That’s completely in-cut time,” explains Steven Horvath. “So with the Jabro cutters, we went from six tools per part down to only two. And cut time dropped from seven hours to about three and a half hours, depending on part size. And while the previous tools were a bit more economical, the Seco tooling is much more cost effective in terms of better performance, higher quality parts and much longer tool life that, in the long run, helps reduce necessary tooling inventory.”
Because the Jabro cutters eliminated the shop’s “one pass/one tool rut,” Horvath and the other cell operators no longer have to physically watch for when cutters wear, as they did for the previous tooling. Plus, using less Jabro cutters frees up additional tool storage positions for redundant tooling that, in turn, increases untended run time and allows one person to handle multiple cells.
While the Jabro cutters do all the hard milling at Build-A-Mold, Seco’s Niagara solid carbide ball and flat end mills handle the lion’s share of the shop’s standard finish machining of non-hardened parts. The shop’s former end mills fell short in cutter life, while, according to Hindi and Horvath, the Niagara cutters not only last longer, they are more cost effective and generate better surface finishes and higher accuracies.
In addition to the Jabro end mills, Seco’s Square 6 high feed shoulder milling cutters and Double Octomill face mills give the HMC cells cutting speed and torque capabilities that were lacking with the shop’s other tooling. Square 6 cutters incorporate trigonal inserts with six cutting edges for increased productivity and lower cost per edge. The tool offers three different insert geometries and three different pitches, enabling it to provide reliable, high productivity in face milling, contouring, plunging, slotting and square shoulder milling.
Build-A-Mold’s Double Octomills are 152.4 mm (6 in.) in diameter and have 10 insert pockets with inserts that provide a total of 16 cutting edges. The cutters work for both roughing and finishing operations, and Seco designed them in a range of three different pitches: Normal, Normal+ and Close pitch. This allows shops, such as Build-A-Mold, to match the right cutter pitch to specific machine power and speed capabilities to optimize productivity for different machines and materials.
Within its EDM electrode machining operations, Build-A-Mold tooled up two new F Series Makino vertical machining centres (VMCs) with Seco Graphflex shrinkfit holders along with some Niagara cutters. Before this, the shop used multiple brands of holders and cutters that all lacked performance consistency, and in many cases, electrode accuracy suffered.
The VMCs run cutters between 0.406 mm (0.016 in.) and 25 mm (0.984 in.) in diameter at spindle speeds between 9,000 and 13,000 rpm. And because electrode geometries continue to advance in complexity and intricacy, the shop must use increasingly smaller diameter cutters that magnify the slightest imperfections in a holder.
The Seco holders ensure both consistency and precision (less runout at the tool tip), as well as better holding power and longer life for many more heating/cooling heatshrink cycles. This combination of advanced tooling (holders and cutters) and the VMCs, according to Paul Van Snick, has eliminated the need to run finished electrodes through the quality control (QC) process after machining. “That’s a huge savings,” he said, “when considering the number of electrodes per job can vary anywhere from two, 50 or 200, depending on part size and surface finish requirements.”
On some of its VMCs machining metal components, Build-A-Mold expanded its use of Seco’s 50.8 mm (2 in.) diameter Highfeed cutters to include 3D roughing operations. And like they do for the shop’s 2D roughing operations on boring mills, the Seco cutters provide significantly longer tool life–up to 7.5 hours of in-the-cut machine time before inserts need indexing–and higher feedrates for 3D roughing.
Beyond milling operations, Build-A-Mold standardized all its reaming operations with Seco Nanofix multi-tooth solid-carbide reamers and Nanofix holders to eliminate sucker pin flashing problems. Sucker pins push out a “slug” of material along with the finish molded part, and a mold can have anywhere from four to 16 sucker-pin holes that are between 50.8 mm (2 in.) and 152.4 mm (6 in.) deep.
Any gap or imperfection between the sucker pin and the walls of the sucker-pin hole will allow a piece of plastic (flash) to stick in the hole and subsequently adhere to the next molded part, basically ruining it. Most people try to remedy the flashing problem by smoothing out the hole’s surface, but that only increases the hole’s size and actually makes matters worse.
Nanofix holders feature adjustable torque specification levels for precisely holding the reamers, and the holder/reamer combination generates mirror finishes that prevent flashing. The tooling combination also allows Build-A-Mold to ream sucker-pin holes in single passes and without pecking cycles to shorten reaming time.
“There’s a fine line between producing a sucker-pin hole that’s too tight or too loose and one that is just right,” explains Jeff Bailey. “For us, perfection rides on surface finish and holding the hole’s 0.0005 in. tolerance. Compared to other standard reamer sets, the Seco tooling far exceeds our expectations.”
Build-A-Mold’s main market segment remains automotive, as it was at the time of the first Seco tooling project. Since then, additional machine tools and more Seco tooling have reduced large part machining (core and cavity parts) turnaround times to around one week, and down to even less time for smaller components.
In addition to tooling, the shop relies on Seco’s tool inventory management as well as its tool-recycling program. The Seco tool inventory replenishment system is a cabinet located on the shop floor and in close proximity to the machines using the tooling. It has eliminated waste and ensures Build-A-Mold always has needed tooling on hand.
What started with one cutter has progressed to Seco tools making up about 80 per cent of Build-A-Mold’s tooling. Plus, the shop has whittled down its previous list of nine suppliers to only three main ones.
“When it comes to suppliers, we focus on service and how well they meet our needs. We want quick responses from suppliers, both in terms of application support and tooling delivery. And in most instances, we have to have next-day delivery,” says Hindi. “From that first high feed milling project, we were very impressed with Seco as a company and with its tooling. Together with them, we continue to reduce tooling costs and inventory and optimize our mouldmaking operations.” SMT