FEATURE ON CNC MILLS & MACHINING CENTRES

Burr-free results using supercritical CO2 coolant

Supercritical CO2 milling of medical plastics using a Mikron Mill S 400U simultaneous five-axis machining centre from GFMS equipped with a Fusion Coolant Systems’ sc-CO2 delivery system produced impressive burr-free results in trials organised by GF Machining Solutions and the Competence Centre for Machining (KSF) at Furtwangen University IFC, Tuttlingen.

Ultra-high molecular weight polyethylene (UHMWPE) is a common material used in medical orthopaedics.The material’s durable, low-friction surface acts as a spacer that ensures mobility for knee, hip and shoulder implants. However, machining this material with traditional milling techniques results in the formation of burrs that often require manual removal in a secondary process.In addition, as the thermal expansion coefficient of UHMWPE is more than 12 times higher than steel, controlling heat during machining operations is essential to achieve the tight tolerances and high dimensional accuracies required for implants.

In recent tests, the effects of using supercritical CO2 cooling (sc-CO2) for the milling of spacers, using a Mikron Mill S 400 U five-axis milling machine equipped with a Step-Tec 42,000 rpm spindle and a Fusion Coolant Systems’ Pure-Cut+ sc-CO2 delivery system, were undertaken. The sc-CO2 is capable of providing CO2 up to 110 bar pressure and includes a Pure-Cut+ MQL delivery system.

Two different spacer cutting trials took place: slot cutting using a 3mm single-blade end mill andfive-axis milling using a 6 mm ball-nose endmill.The results obtained in both trials indicate a significant reduction in burr formation, improved workpiece accuracies and better surface quality.These factors point toward a more reliable machining process that may greatly reduce, or even eliminate, manual deburring.
For further information www.gfms.com

Start-up invests in MACH MDS 845-8T mill

MACH Machine Tools has supplied PMR Developments & Engineering, a precision subcontract specialist start-up, with a new tool-room mill. Now in situ at the company’s Hereford facility,the three-axis MACH MDS 845-8T features theDynaPath WinDelta CNC.
The MDS 845-8T is the most recent machine tool investment made by PMR in its three-year history and has taken its place alongside a new mini mill and a pre-owned two-axis lathe.

PMR’s new MDS 845-8T machines a range of precision components, including injection mould tool inserts and associated parts for a number of customers in the automotive and medical sectors, as well as new and replacement industrial equipment parts.These parts, typically machined in small volumes from a range of different materials, are characterised by their tight geometric and dimensional tolerances, and their high surface finishes.

To meet lead times and ensure that PMR achieves its machining contract requirements on time and in budget, the company regularly pushes the MDS 845-8T’s capabilities to the limit in order to reduce part cycle times.Where feasible, PMR deploys high material removal rates involving extended depths of cut and optimised speeds and feeds.

Says William Homes, PMR’s owner and director:“Our investment in the new MDS 845-8T has significantly increased our machining capacity and capabilities. The machine is powerful, fast, accurate and flexible and, although classified as a ‘tool-room mill’, such is its technical specification and processing capabilities that it’s much more production-oriented.”

He adds: “The versatility and flexibility of the DynaPath control system are also impressive. “Straight-off-the-bat, we liked the control’s large 15.6” LED touchscreen, its clear and logical navigation, and its simple-to-use and understand menus and operation screens, which all help reduce set-up times and prevent input errors.”
For further information www.machmt.co.uk

700% growth in three years in partnership with XYZ

James White joined NSK Precision Engineering in 2015 and took the company over in 2019, making a new CNC machining centre his top priority. His research led him to invest in anXYZ 750 LR with 750 x 440 x 500mm travel, Siemens 828D control (with optional ShopMill), and linear rail technology for fast acceleration and deceleration rates.

“XYZ Machine Tools listened to where we wanted to take the business, asking the right questions, showing that they understood how our company works,” he says.“They also came up with an attractive solution to get our CNC machining capacity started. We already had a 1994 XYZ turret mill with ProtoTRAK control, which is used daily, so this gave us extra confidence in our decision.”

Taking over NSK Precision Engineering, which has been in operation since 1995, was a steep learning curve, figuring out how to manage both the workforce and the day-to-day administration of the company. Additionally, White relocated the company from its previous 1500 sq ft factory to a new 10,000 sq ft site near Reading, while growing turnover by 700% and increasing his workforce from two to seven.

“Previously, we were subcontracting a lot of work to local companies,” he explains.“Investing in CNC has enabled us to take this work back in-house, which gives us more control over quality and delivery while at the same time improving our profit margins. At the old factory, we were limited for space, restricting which XYZ machine we could choose. With the new factory and the increase in workload we’ve been able to make a further investment in a XYZ 1000 LR with 4th-axis rotary table, Siemens 828D control with the ShopMill option, expanded 24-station tool carousel and a swarf conveyor.”
For further information www.xyzmachinetools.com

VMC makes low-cost jobs financially viable

Many prismatic machining contracts ideally take place on a five-axis machining centre, which enables components to be produced cost effectively. A problem arises, however, if the parts do not command a high selling price.

Subcontractor G&J (CNC) Services in Paddock Wood has apparently found a solution: the Leadwell V-30iT 3+2-axis BT40 machining centre from WH-Lead, which says the entry-level price of less than six figures belies the five-axis machine’s extensive capabilities. According to G&J (CNC) Services, the hourly rate that the subcontractor charges based on the investment allows the efficient production of less complex prismatic components at prices which compare favourably with those quoted by competitors in low-wage countries.

The company’s owner Charlie Naismith says: “Depending on the value of the parts being machined, which is normally down to their complexity and the material used, you have to make sure the figures add up. Much of our throughput is fairly simple 3+2-axis work in mild steel and aluminium that customers will not pay a premium for, so the Leadwell machine is perfect.

Continues Naismith: “We actually use it in three-axis mode for much of the time, but the five-axis functionality is there for when we need it, saving costs associated with workholding, handling and work-in-progress. At the same time, it helps with accuracy by being able to access parts with shorter tools and by cutting down on manual re-fixturing.”

He also appreciates the ergonomics of the V-30iT, pointing out that the rotary table when flat is at the same level as the fixed table, so there are no clearance issues. Control is provided by a Fanuc 0i-MF Plus, although Siemens, Fagor and Heidenhain are optional, as is the specification of 4+1 or full five-axis interpolation.
For further information www.wh-lead.co.uk

Subcontractor opts for second DNM 4500 VMC

Mills CNC has supplied subcontract specialist EDM Precision Technologies with a new vertical machining centre.The machine, a compact DN Solutions three-axis DNM 4500 equipped with Siemens 828D control, now sits adjacent to the company’s first DNM 4500 machining centre, acquired in 2018, to create a flexible, high-productivity milling cell.

EDM Precision’s new DNM machine has the exact technical specification as the first, featuring: a 12,000 rpm BT40 spindle with though-spindle-coolant capability; 30-position ATC; and 1000 x 450mm worktable with 600kg load.The latest DNM 4500 also features a Renishaw tool and workpiece probing systems for fast and efficient set-ups.

Says owner and managing director Paul Waldron:“Our first DNM 4500 proved to be a great investment and a huge success. The machine is fast, accurate and reliable, so when we were looking to upgrade our in-house milling capabilities still further, we decided to go ‘like for like’ and order a second DNM 4500.”

The company’s customers are diverse and operate in the motorsport, aerospace, medical, automotive, defence, and scientific equipment and instrumentation sectors. They also include a significant number of universities and research institutions. All have high demands. For instance, part accuracies of ±5 µm and surface finishes down to Ra 0.8µm are tight and non-negotiable.Turnaround times are equally demanding.

EDM Precision’s new DNM 4500 is clearly important and integral to the company’s ability to meet its customer’s promises.

Concludes Waldron:“Our new DNM 4500 is a great performer and, since being installed, hasn’t missed a beat.The machine was delivered and installed quickly and with minimum disruption and, as intended, has fast become a valuable asset that will facilitate significant growth in the future.”
For further information www.millscnc.co.uk