# Stochastic Evaluation of Cutting Tool Load and Surface Quality during Milling of HPL
## 1 Introduction  
Machining is one of the most important and widely used manufacturing technologies [1]. Traditional machining methods include milling, which is the chip machining of material with a multitool, where the cutting speed is determined by the rotation of the cutter around a fixed axis, and the feed rate is given by the movement of the workpiece.  
The cutting speed and feed rate are vector quantities; depending on the direction of the vectors, we can distinguish between down milling (in which the vectors have the same direction) and up milling (in which the vectors have opposite directions). It is well knownthat both of these techniques entail different machining flow during the cutting process. In particular, there are changes in cutting forces and temperature gradients during milling [2; 3], which will affect the overall integrity and quality of the machined surface [4; 5; 6].  
The subjects of this article are measurements performed on a selected machine tool, which is a new milling cutter with brazed cutting edges, under defined cutting conditions in down milling and up milling. The material to be machined is high-pressure plastic-laminate composite material, HPL, which is often used in both the construction and furniture industries. High-pressure laminates generally consist of fibrous reinforcing materials and resin binders, where the combination of heat and pressure produces a highly durable product. They can also be produced with antimicrobial properties [5; 7; 8; 9].  
The solution was realised at the Department of Applied Mechanics and at the Department of Machining, Assembly and Engineering Metrology, Faculty of Mechanical Engineering, VSB--Technical University of Ostrava (Ostrava, Czech Republic) in cooperation with the company VYDONA s.r.o. (Holesov, Czech Republic), which produces machine tools [7; 10; 11; 12].  
The obtained results, i.e., the force and moment load of the tool used and the quality of the machined surface, expressed by the achieved surface roughness, are statistically evaluated and displayed using bounded frequency histograms with their stochastic parameters. The results can be used practically, in design, strength analysis, and in the determination of the service life of cutting machines and machining tools, or the setting of optimal production technology. There is not enough information about the statistical evaluation of HPL material machining. However, stochastic approaches applied in the branch of mechanical engineering are widely accepted and used.  
Time records of force and moment loads on the tool during milling are a typical stochastic process in mechanics [13; 14; 15; 16; 17; 18].  
The motivation for this article was a general lack of information on the machining of HPL material. This article aims to fill this information gap. We did not find enough information in the literature and did not find any literature about the milling mechanics of HPL material.  
Marginally, the article is also focused on the finite element solution as well as the material properties and design of cutting tools [19].  
The contribution of this paper is mainly the evaluation of the surface quality of machined surfaces in addition to the measurement of dynamic loads in the cutting tool and its evaluation.