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From design directly to production

Speck Pumpen, a medium-sized manufacturer of liquid and vacuum pumps, optimized its process chain, from design to production. The aim was to implement the parallel and short-term production of prototypes during the design process. The results obtained from the pilot series and functional testing of the prototype were to be incorporated back into the design process right away.

Process optimization at Speck Pumpen

The calculation and simulation of the flow behavior of liquids and gas mixtures necessary for pump design has been complex and error-prone since time immemorial. Even in simple systems, it is difficult to make statements about the real-world behavior based on the theoretical models, and this requires many years of experience and expertise. It is exactly these key skills, coupled with a very high capacity for innovation, that has enabled Speck Pumpen to maintain a leading position on the liquid and vacuum pump market for decades.

With each new design, the manufacturer approaches theory and practice on parallel paths. Using complex simulation software, initial ideas for a new pump first undergo a theoretical check, and the result is a preliminary constructional sketch in the CAD system. Following these guidelines, a prototype is built to perform the first function tests.

Based on these conditions, Speck Pumpen wanted to install a process chain to optimize its development process. The problem with the existing process was due to the different CAD systems in prototyping and manufacturing and construction. This made the data exchange between the systems and the joint work with identical design data more difficult.

The aim was therefore to use the new solution to create the NC programs directly from the shared CAD data of the constructional sketch. To do so, a common CAD system had to be introduced in the existing process and connected to the existing Mastercam CAM system. An adapted SINUMERIK postprocessor should generate the NC programs from the CAM data to produce the first functional models.

Another concern was to adapt the geometry of the pump components to the production process without affecting their function. The cast blanks for the pumps are generally prefabricated at an external site, but require a series of mechanical alterations to the casing and impeller before the pump is finally finished. These downstream work steps should already be optimized in the design. The production preparation is therefore already included during the first stages of development to avoid obstacles in the subsequent production and to account for economic considerations.

SolidWorks and Mastercam

When it came to a 3D CAD system, Speck Pumpen chose SolidWorks. "We especially liked SolidWorks' parametric operating principle. Since we design using many cast blanks, they are first created as a raw part and the finished part is included as a feature," designer Mr. Wohlleben said, explaining the decision. "Another reason for the decision was the fact that the production planning had already had positive experiences with SolidWorks and the learning curve would thus be reduced," production manager Dieter Meier said.

The CAD system was installed and networked by unicam in the design and manufacturing. A basic ERP system (Enterprise Resource Planning) from abas was used as a workflow and archiving system. This controls, among others, the version and rights management in the process. The entire process chain was adapted by unicam in accordance with Speck Pumpen's requirements, enabling the smooth collaboration of design and manufacturing.

Using Mastercam, the SINUMERIK specific NC programs are created using 3D design data from SolidWorks. For the first use of the optimized process chain, the unicam postprocessor was set up specially on the DMU 65 monoBLOCK five-axis milling machine, equipped with a SINUMERIK 840D sl controller and the SINUMERIK Operate user interface. The experienced Mastercam team in Speck Pumpen's production planning was able to implement the specifications from the design in NC programs and produce the first prototypes within a short time.

SINUMERIK in series production

Permanent process optimization is an important matter at Speck Pumpen and has already run in series production in numerous projects. The machine equipment is primarily based on CNC machines with SINUMERIK controls. This control has proved itself over the long term because of the wide range of programming options and the openness for automated series production. The machinery includes simple CNC machines for brushing, grinding, and deburring of castings, as well as complex five-axis milling machines and multi-channel rotary milling machines with SINUMERIK 840D sl and SINUMERIK Operate controls.

In production, all the options of the machines and the controls can be used for highly efficient operation. The production processes are fully automated and require no operator, with feeding and onward transport between the processing units, such as between milling and vertical turning machines. Automated measurement and testing procedures ensure compliance with the high level of quality.

The programs for series production are created in the planning operation with Mastercam or CNC editors. Only in individual cases is the programming carried out directly on the machine. Due to many years of experience, Mastercam was the specified CAM system for the new process chain.

Extensive SINUMERIK command set

One reason for the use of a SINUMERIK control in series production at Speck Pumpen is the large command set. For example, it was possible to optimize the variant production of long shafts by using R-parameters. The turning of the shafts takes place in the main and counter spindle with flying clamps. The variants of the different shaft types are programmed in the main and sub-programs via freely definable R-parameters, or other sub-programs are called automatically depending on type. The right values for this shaft type are pre-assigned to the R-parameters for manufacturing. This makes it possible to create variants of a shaft type with a set of NC programs, allowing the production process to be flexibly adapted to changes in a shaft type.

During the execution of the NC programs, the current processing status is also stored in R-parameters as protection against power failures. In the event of a stop, such as due to a power outage on the machine, the NC program and thus the processing can be resumed again very simply at the point of interruption. When the NC program is restarted, the stored values ​​of the R-parameters are recognized and the relevant sub-program continues from the point of interruption. Damage to the workpiece or machinery can therefore largely be avoided.

Open for special solution

In addition to the large command set, the diverse programming options are another reason for using the SINUMERIK control. A typical task in production at Speck Pumpen is the boring of holes outside the axis of rotation. The borehole walls are functional surfaces and must meet high standards in terms of surface finish and geometric tolerances. Milling machines with a rotary table are used here. To achieve the high surface quality, both the rotary table and the boring tool must be operated at the highest possible speed. Due to the counter-rotating movement of the rotary table and boring tool, the two speeds combine to achieve high relative cutting speeds at the tool tip.

Since the boreholes are located outside the axis of rotation of the table, the boring tool must perform compensating movements of the X and Y axes during the rotational movement of the table to remain at the center point of the borehole. A special solution was developed especially for this application. Using automatically generated correction tables, the rotary axis positions of the milling table are assigned the correction values ​​in X and Y to perform the compensation movements during the execution of the program – a special programming solution that has proved itself in use.

Successful new development – applied to the introduced process chain

During the new development of the BluVac liquid vacuum pump, the newly introduced process chain demonstrated its performance capability. This type of pump is used in the production of plastic profiles by means of extrusion. In this manufacturing method, viscous plastic material is forced through a shaping aperture, thus obtaining the required profile. The shape of the profile is retained during the cooling phase on a so-called calibrating table. For this purpose, the extruded plastic profile is pushed through a calibration sleeve, in which a vacuum sucks the profile onto the inside walls. Water flows around the profile for faster cooling. The pump maintains the vacuum at the predetermined underpressure during the cooling process.

The aim of the new development was to technically optimize the pumping system in terms of flow and function so that, in combination with intelligent control, high efficiency could be achieved with low maintenance overhead.

With the help of the process chain installed by unicam and Siemens, the set goal was fully achieved. In operation, the new liquid vacuum pump saves up to 67 percent energy compared to existing systems. For Speck Pumpen, the investment in the new process chain has therefore paid off. During the design phase, prototypes can now be built and tested very quickly and the results incorporated into the design. It was thus possible to develop the new BluVac generation of pumps further to secure it a decisive advantage over its competitors.