• The paper presents experimental testing results of cutting power of thermally modifi ed wood of Scots pine (Pinus sylvestris L.) during lengthwise milling. The process of heat treatment was performed in the atmosphere of superheated steam, at temperatures of 130, 160, 190 and 220 °C, maintaining

Objectives The aim of the study was to determine the effect of parameters of the thermal modification process and machining on the size distribution of dust particles of Scots pine (Pinus sylvestris L.) generated during lengthwise milling. Method Unmodified wood and thermally modified wood at temperatures of 130, 160, 190, and 220°C were milled lengthwise at cutting depths of 0.5 and 2 mm. Particle size analysis was done using the sieving method. The content of the finest particles was measured using the laser diffraction method. Results The results indicate that at smaller cutting depths, more smaller particles were formed regardless of the wood modification temperature. Thermal treatment of wood does not cause significant differences in the general particle size distribution of dust. However, the content of the finest dust particles depends on the temperature of wood modification. When machined, wood thermally modified at higher temperatures results in the formation of more dust particles that may pose health risks to employees. This is particularly noticeable at a smaller cutting depth. Conclusion With the increase of the temperature of the modification, the share of the finest dust particles, which are a potential threat to the health of employees, increases. To reduce dust emissions during milling of thermally modified wood, the highest possible cutting depth should be used.

The article presents research on the effect of the sharpness angle on the quality of machined surface of native wood species (pine, beech, and black locust) and an exotic species called iroko. Four sharpness angle values were analyzed at 25, 40, 45, and 55°. The experiment was conducted on a bottom-spindle milling machine, with a constant spindle rotational speed (6000 min-1) and four feeding speeds of 3.2, 8.3, 12.5, and 16.7 m/min. The influence of sharpness angle, feeding speed, and wood species on the quality of machined surface of wood was determined. The optimum ranges of the sharpness angle were established with respect to wood surface quality. The surface roughness of the samples decreased with decreasing in the sharpness angle in range of 55° to 40°. The optimal value of the angle was 40°, and the roughness increased with increasing feeding speed. It was found that an increase in wood density decreased surface roughness.

The surface roughness in plane milled Scots pine wood that was thermally modified at 190 °C and 220 °C was examined. Indicators of wood surface roughness included the three most commonly applied parameters, arithmetic mean surface roughness (Ra), surface roughness depth (Rz), and total height of the roughness profile (Rt). Roughness was tested separately for earlywood and latewood using two feed speeds of 1 and 5 m/min. The thickness of the milled layer was 1 mm. The effect of all controlled factors, i.e., feed speed, temperature of modification, and place of measurements, on the parameters of surface roughness were statistically significant (P < 0.05). Surface roughness increased with an increase in feed speed, whereas it decreased with an increased modification temperature. Latewood was characteristically lower in roughness than earlywood. The greatest differences in homogenous groups for the determination of the roughness parameters were found in measurements taken on earlywood and latewood, while the smallest differences were recorded for different feed speeds.

Introduction. A wheelchair is a special vehicle designed specifically for people with walking limitations. One of the types is an active wheelchair. This is a manually propelled wheelchair, the design and structure of which maximise the mobility of its given user at the expense of accepted instability. Objective. The aim of this study was to identify and present a hierarchy of potential incidents causing a health hazard and reducing the mobility of individuals with ambulatory disability who use active wheelchairs in non-urban settings. Materials and methods. Information about incidents connected with wheelchair use was collected from interviews with disabled individuals, based on a questionnaire. Recorded data were analysed using the Preliminary Hazard Analysis (PHA). Results. The results comprise a list of hazards for wheelchair user with ascribed priority numbers metrising their significance.Conclusions. An ordered list of hazards connected with wheelchair operation situations is useful when designing active wheelchairs and when learning the technique of wheelchair riding.