With the corporate claim exactly yours, experts of the LMT Tools Group promise their customers to offer exactly the solution they actually need. This promise encompasses customized tool solutions which stand out against standard solutions and, at the same time, feature the latest tool research innovations. This guarantees users that their production is operating at top efficiency.
Using innovative development methods and new production processes such as the computer aided simulation of machining processes or the construction of prototypes using the additive production process 3D printing, today, tool concepts can be optimized easily and fault-free and adapted to customer requirements. For example, prototypes of milling and threading tools can be created before work is started at the customer side in order to then quickly and reliably fulfill the requirements of the final application in terms of efficiency while avoiding unnecessary costs.
Even customized high-performance coatings and innovative cutting material configurations contribute significantly in this regard. Below are a few examples of the ways in which effective customer-specific tool solutions are implemented.
Without innovative tool coatings, it would be impossible to meet the permanent demand for increased machining performance. It is essential that layer properties are precisely adapted to the specific application. This is where our own coating center – in addition to excellent know-how – comes into play, allowing us to customize solutions to customers’ needs. In Germany, the LMT Tools Group even has two coating centers, one at LMT Fette and the other at LMT Kieninger, where new coatings are constantly being developed.
One innovative example is our “Nanomold Black” coating. It closes the application gap between the already established high-performance coatings “Nanomold Gold” and “Nanomold Red” (image 1). While the gold coating is the first choice for roughing and semi-finishing materials in the lower hardness range and the red coating displays its true performance during the finishing of hardened materials up to 65 HRC, Nanomold Black covers a more universal application range. It is highly suitable for machining steel, cast steel and cast iron up to a hardness of 56 HRC.
Customized rolling heads
Thread rolling systems are part of the important core competencies of LMT Fette. The proven user benefits of thread rolling compared to thread cutting are extremely short production times combined with highest thread stability, constant dimensional accuracy and excellent surface quality. The brand new and very user-friendly LMT Fette axial rolling head EVOline was launched very recently and has since proven itself many times over.
Then, a further step in increased efficiency for non-cutting thread production was presented: The “CTline” (customizable tangential rolling heads) concept.
“Customized” refers to customer-specific solutions through modifications to standard rolling heads. The advantages of this concept range from even greater customization of production performance to shorter delivery times in comparison with traditional special solutions. Here, we focus on customer-specific requirements for the component, the machine tool and the machining process as well as individual customer goals. Even slight changes to tool making, tool stability or coolant supply can significantly increase rolling head efficiency or make efficiency possible in the first place, as opposed to what was possible with standard solutions. Hence, each CTline rolling head is one of a kind.
3D printing, an additive manufacturing method, is also used to develop solutions more quickly and to optimize functionality.
Image 2 shows a tangential thread rolling head by LMT Fette as example. The transparent upper joint with integrated coolant supply was 3D-printed. Following this, several rolling head holders made of steel with a tensile strength of 1,000 N/mm2 and integrated coolant supply were printed and are already operative. It was possible to reduce the weight of the holders by 43%. Thereby, additional ecological requirements are met with regard to weight and material.
Higher quality of life
Our motto exactly yours is, however, not realized only through the implementation of customized designs and applications of precision tools. The LMT Tools Group also fulfills this promise in the truest sense of the word through the customized processing of personal products such as hip and knee prostheses (image 3) thereby contributing directly to the well-being of people.
Designing and manufacturing prostheses is not an easy task to do. They must resist high strains and function immaculately for a long period of time. The proper functioning of these high-tech implants do not depend solely on the expertise of the surgeon but to a very large extent on the quality of the applied cutting processes. The focus is here on new materials, innovative manufacturing methods and correspondingly adapted tools. Perfect matching of all crucial parameters then helps to improve the patient’s quality of life.
A knee prosthesis mainly consists of three parts: the upper part (femur), the lower part (tibia) and the kneecap (patella) that joins the upper and the lower part. The upper and the lower part are made of titanium (TiAl6V4) or a CoCrMo alloy. Sometimes, ceramics are used, too. Compared to others, an implant made of titanium light while offering high wear resistance but is more expensive. Generally, materials used in medical engineering must be corrosion-resistant, biocompatible and have a thermal expansion that is as low as possible.
The kneecap is made of plastic (polyethylene) and absorbs the impact stress of the joint. Furthermore, it reduces the friction. Here it becomes clear, that the generated surface roughness of the expansion surfaces of the prosthesis will have a decisive influence on the lifespan. Therefore, metallic parts are not only subjected to finish processing with milling tools but also undergo a grinding and polishing procedure.
Contrary to this, surfaces that are not somehow kinematically related need a totally different surface finish. They must be rougher or have a microstructured surface to ensure that the bone tissue adheres to the prosthetic after it has grown in. The use of coolants should be avoided during milling of these surfaces to avoid that the metal pores get clogged up. In addition, the surfaces are sandblast after completion of the cutting process.
The objective: Increased efficiency
So far, HSCline solid carbide ball nose end mills with a diameter of 10 mm have been used for roughing and finishing processing of the rounded-off outer contours of the upper part of the knee implant (image 2). The
contour was processed line by line. The milling parameter and the achieved surface quality met the requirements, however, the aim was to significantly reduce the processing time and, thereby, the costs.
The LMT Tools application experts opted for a solution especially designed for this case and now offer users form mills by LMT Fette with convex cutting edges, i.e. cutting edges curved to the inside (image 4). The curve radius corresponds to the outer contour of the workpiece. It was, thereby, possible to replace the slow line-by-line milling with the mill positioned perpendicular to the feed direction by integral cutting over the entire contour with the mill positioned in parallel to the feed direction. And the result is impressive. The milling time required for roughing and finishing was reduced from 45 minutes to 2.5 minutes. The manufacturing costs were thereby reduced by 85%.
The examples mentioned above show that the use of high-performance tools is not all that counts. The LMT Tools specialists also adapt the correct milling strategy to the specific application and align the cutting values both with the material to be processed and the geometrical properties of the component as well as with the specific machine conditions. It is only by this holistic approach that the customer can achieve the desired objective.
Author: Dr. Diethard Thomas, LMT Consultant