Jimmy Johansson

Controllable cutting performance is essential for handheld saws in both craft and professional wood processing. Despite the widespread use of side-bevelled handsaw teeth in manual and electrically powered tools, the combined influence of tooth geometry, set pattern, as well as cutting direction on cutting forces is not well understood. A Design of Experiments (DoE) approach was applied to evaluate the effects of tooth type (universal, UT; compound, GT), side-bevel, set, set pattern, and cutting direction on main ( F _m ) and normal ( F _n ) cutting forces. Experiments were conducted on Norway spruce blocks sourced from a single log, which was conditioned to achieve uniform moisture content and characterised using X-ray computed tomography. A custom-built cutting rig measured F _m and F _n under controlled cutting speed and depth conditions. A 2⁵⁻¹ fractional factorial design was applied as an exploratory DoE screening approach to capture main and two-factor interaction effects. F _m was dominated by cutting direction and kerf-related factors, with GT teeth exhibiting lower F _m than UT teeth in rip cutting. F _n was primarily governed by tooth type, bevel, and set pattern. Interaction effects between geometry and cutting direction were statistically significant, highlighting the multivariate nature of the cutting process. Overall, cutting forces are governed by interactions between tooth geometry, set configuration, and cutting direction. The results provide a quantitative basis for further development of handsaw tooth design and cutting efficiency.

The Swedish furniture industry is dominated by low-volume, high-variety production, with only a few firms operating high-volume models. Although interest in remanufacturing is increasing, its implementation remains limited. This study aims to strengthen circularity in the Swedish furniture industry, focusing on remanufacturing in SMEs with low production volumes and high product variety. Empirical studies with five manufacturers were conducted as part of a collaborative research project, and the data were analysed through ecosystem, circular strategy, and manufacturing strategy perspectives. The companies exhibit similar product variety, production volumes, and manufacturing strategies, but they adopt circular strategies differently, ranging from reuse and repair to remanufacturing. Multiple intermediaries in the ecosystem reduce product traceability, and the absence of information exchange with customers further constrains circular flows. The study identifies a progression towards remanufacturing that begins with customer-specific remanufacturing, develops into hybrid production combining new and remanufactured products, and ultimately requires strategic decisions on dedicated systems or outsourcing as volumes increase.

Full-Field Force Mapping of Cutting Forces Driven by Local Density Variations in Norway Spruce WoodLocal density variations in wood influence cutting performance. In this study, full-field force mapping was applied to investigate the relationship between density distribution and cutting forces. Cutting forces were measured using piezoelectric transducers during cutting of Norway spruce. X-ray computed tomography (CT) scans of the workpiece provided spatially resolved density data. Force maps were constructed by aligning recorded forces with kerf positions and CT data. Results showed that cutting forces increased in regions of higher density, particularly near knot boundaries and latewood zones. Inner knot areas exhibiting lower density correlated with reduced cutting forces. Normal-force patterns were less responsive to local density changes. No self-feeding behaviour was observed. The integrated CT–force mapping technique enables spatial analysis of cutting responses in relation to anatomical wood features.

Kaskadanvändning och cirkulära perspektiv på skogsbränslen och biprodukter

Surface-checking is a significant quality issue of veneer and sliced lamellae-based wood products. This study explores how surface-checking in sliced lamellae-based engineered wood Flooring (EWF) is influenced by two key structure parameters: core type and top-layer thickness. The core types assessed were a standard solid wood lamellae with a veneer back-end layer (S), a standard solid wood lamellae core with veneer back-end layers on the two sides (DS), and a single-layer oriented strand board (OS) core. The EWF element’s top-layer lamellae were plain sliced at nominal dimensions of 1.5, 2.5, 3.5, and 4.5 mm from freshly sawn slabs of European oak (Quercus spp.). The surface-checking of EWF specimens was quantified based on a digital image correlation (DIC) method, which outputs a surface-checking index. The surface-checking results were evaluated using a Tweedie compound Poisson data distribution to fit a general linear model. The model evaluated the impact of individual factors, sliced lamellae thickness and core type, and their interaction. The checking index confidence intervals were estimated using a bootstrapping technique. Findings reveal a significant interaction between studied factors and provide insight into optimizing top-layer thickness and core construction to diminish surface-checking. A low sliced lamella thickness on standard solid wood lamellae core resulted in low surface-checking, deemed relevant for further research.

The mechanical properties of sliced lamellae are critical for structural and decorative engineered wood products. This study evaluates the impact of slicing thickness on the tensile mechanical properties of plain oak (Quercus robur L. and Quercus petraea L.) sliced lamellae, perpendicular to the grain direction. The mechanical performance parameters in terms of the modulus of rupture (MOR), strain at break, and modulus of elasticity (MOE), were analysed using a one-way analysis of variance (ANOVA) and contrast analysis. Our findings indicate that slicing thickness substantially affects the mechanical properties of the modulus of rupture and strain at break, whilst the modulus of elasticity was somewhat independent of the slicing thickness. The mean MOR value increased from 0.8 to 1.43 N mm⁻² for an increase in the sliced lamellae thickness from 1.5 to 4.5 mm. The strain at break increased, on average, from 1.37 to 2.64% for an increase in the sliced lamellae thickness from 1.5 to 4.5 mm. The MOE was approximately 100–120 N mm⁻², indicating a substantially reduced stiffness compared to other sliced lamellae species and solid oak reported values. The slicing check depth ratio diminished from approximately 69% to 50% for an increase in the sliced lamellae thickness from 1.5 mm to 4.5 mm. These findings indicate a negative correlation between the slicing check depth ratio and the tensile performance perpendicular to the grain, suggesting the importance of obtaining an optimal slicing quality. This study employs digital image correlation (DIC) analysis to gain insights into the fracture mechanisms of the tested sliced lamellae and provides an alternative method for strain and stress measuring. The DIC analysis highlighted the role of slicing checks in the stress concentration and ultimate failure areas. This research provides insights into the fracture behaviour of sliced lamellae that are perpendicular to the grain, which is critical for the performance of both structural and decorative products.

The lack of quantitative methods for surface-checking measurements may hinder improving the product characteristics of engineered wood flooring products built with sliced top-layer lamellae. This study evaluated the digital image correlation method for its applicability to surface checking measurements in engineered wood flooring elements with the top-layer comprising the plain sliced lamellae of oak (Quercus spp.) species with nominal thicknesses of 1.5–4.5 mm. The method involves observing full-field surface displacements of the sliced lamellae-based wood flooring specimens subjected to an accelerated sorption/desorption cycle. Detection of surface checks relates to discontinuities in surface displacements which can be interpreted from the output strain data as strain peak regions. Additionally, a surface-checking index was defined to describe the extension of surface-checking. Exposure tests were performed on a combination of coating presence and a different number of testing cycles. The main findings provide insight into the method procedure parameters, such as exposure duration, climate conditions, analysis parameters and recommendations regarding the digital image correlation setup settings and specimen manufacturing.

Identifying present drivers of product development and describing roles of identified actors primarily affecting the development of harvesters: a multiplecase study Gustafsson Å., Johansson J. (2022). Identifying present drivers of product development and describing roles of identified actors primarily affecting the development of harvesters: a multiplecase study.

In this paper, a new method of measuring slicing checks for flat-sliced veneers was evaluated. The method is based on image analysis of veneer cross-sections, having highlighted the slicing checks using surface staining. The segmentation of the checks consists of global thresholding followed by some morphological operations. The outputs of the algorithm are check depth ratio and check frequency. The method was tested on flat-sliced oak (Quercus robur L. and Quercus petraea (Matt). Liebl.) veneers of different thicknesses (1.5, 2.5, 3.5 and 4.5 mm). Two distinct wood qualities and two different cutting directions (lengthwise-sliced and plain-sliced veneers) were evaluated. The algorithm performance resulted in an overall accuracy of 85% enabling an accessible method for relatively fast and accurate measurements of slicing check characteristics in lamella cross-sections. Regression analysis indicated a lack of fixed bias but the presence of proportional bias with the presented method. Check measurements indicate that by varying cutting parameters, it is possible to achieve desired check characteristics independent of slicing thickness. The semi-automated slicing check detection method could benefit further research and optimisation of the slicing process parameters and pave the way towards industrial quality control of slicing checks. The intended area of application is veneer-laminated products for interior use with the focus on veneered wood flooring.