Comparative Surface Quality of Larch (Larix decidua Mill.) Fretwork Patterns Cut through by CNC Routing and by Laser

Round 1

Reviewer 1 Report

The paper presents an experimental work for the determination of the influence of the cutting angle with relate to the grain on the surface quality of larch wood (Larix Decidua Mill.) cut through by laser and CNC routing at different feed-speeds. The research considered geometric fretwork patterns derived from triangle, where the cutting angles with relate to the wood grain were 0°, 15°, 30°, 45°, 60°, 75° and 90°.  

The structure of the paper is very good. The methodology and results are clearly presented, especially graphs.

On the other hand, the conclusion must be improving and the results must be specified and compare with other scientific works. 

The references must be improve - add more papers with this topic with are more suitable to this paper.

Author Response

The paper presents an experimental work for the determination of the influence of the cutting angle with relate to the grain on the surface quality of larch wood (Larix Decidua Mill.) cut through by laser and CNC routing at different feed-speeds. The research considered geometric fretwork patterns derived from triangle, where the cutting angles with relate to the wood grain were 0°, 15°, 30°, 45°, 60°, 75° and 90°.  

The structure of the paper is very good. The methodology and results are clearly presented, especially graphs.

Authors:

We thank the reviewer for the kind appreciation and the suggestions for improvement!

On the other hand, the conclusion must be improving and the results must be specified and compare with other scientific works. 

Authors:

The conclusion chapter was improved.

The results for Rk were presented as mean values, standard deviation and significance.

The results were compared with other scientific works. For example, a paragraph was introduced in line 244: „The findings are in agreement with Goli et al (2002), who found, when CNC milling Douglas Fir, with a feed speed of 5 m/min, that for small angles (10º-20º) the occurence of pull-out material is limited, but fuzzy grain is formed, while for greater angles, the pull-out phenomenon becomes more important. An explanation comes from Goli et al (2004) who analysed the wood surface defects occurring by milling under different angles. When the wood reaction against splitting is higher than the strength of material, surface failure occurs and this appears when cutting takes place under an angle different than 0º with relate to the grain”.

Also, in line 280: „Somehow similar, Pa, for Douglas Fir processed by milling at 5m/min feed speed, suddenly increased for 30º and then again for 70º, in down milling against the grain (Goli et al, 2002).”

line 301: „Laser seems to have more pronouncedly carbonized earlywood especially at the annual ring limit creating gaps below the processed surface (Figure 13), observation made also by Kudela et al (2021)when examining spruce engraved by the laser .”

The references must be improve - add more papers with this topic with are more suitable to this paper.

Authors:

New references were added:

1. Paiu, I.; Cosereanu, C. Fretted Panels Made of Plywood and Beech Wood. Comparison and Quality Evaluation by Stereo Microscopy. Pro Ligno 2021, 17(2); pp. 45-54.
2. Sofuoglu, S.D. Determination of Optimal Machining Parameters of Massive Wooden Edge-Glued Panels Made of European larch (Larix Decidua Mill.) using Taguchi Design Method. BioResources 2015, 10(4), pp. 7772-7781.
3. Magoss, E. General Regularities of Wood Surface Roughness. Acta Silv. Lign. Hung 2008, 4; pp. 81-93.
4. Goli, G.; Bléron, L.; Marchal, R.; Uzielli, L; Negri, M. Formation and quality of wood surfaces processed at various grain angles-Douglas Fir and Oak. Proceedings of the 4th IUFRO Symposium Wood Structure and Properties 02. September 1-3, 2002, Bystra, Slovakia, Ed.Kudela, J., Kurjatko, S., pp.91-98, ISBN 80-967088-9-9.
5. Goli, G.; Marchal, R.; Uzielli, L Classification of wood surface defects according to their mechanical formation during machining Proceedings of the 2nd International Symposium on Wood Machining – Properties of Wood and Wood Com-posites Related to Machining, Vienna, Austria on 5-7 July 2004, ISBN/ISSN: 978-3-9501315-2-9..

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript "Comparative surface quality of larch (Larix decidua Mill.) fretwork patterns cut through by CNC routing and laser at different angles with relate to the grain" presented the experimental work for the determination of the influence of the cutting angle with relate to the grain on the surface quality of larch wood (Larix Decidua Mill.) cut through by laser and CNC routing at different feed-speeds. The authors present an interesting topic, methods are well described and results discussed. Minor revisions are needed:

1. It is necessary to think about the title of the article. I propose to simplify and not replace the abstract with the title of the article. 
2. Line 39 literature cited in this way is not professional. Please describe in more detail.
3.  The article does not set assumptions (hypotheses) that would better support the scientific contribution.
4. In Figures 17, mark the laser method with a different line type (dashed line).
5. The authors present the measured values ​​of the monitored parameters in graphs. The article needs to be supplemented in the discussion and conclusion with the results of the mutual synthesis of measurements. It is necessary to clearly determine which of the changed parameters (angle, sliding speed) has the greatest or least effect on the resulting surface quality. Due to the number of monitored parameters, I recommend using the statistical evaluation method.
6. The conclusion should be supplemented by recommendations that ensure the best quality of the treated surface. Describe the pros and cons of CNC versus laser surface treatment.

Author Response

The manuscript "Comparative surface quality of larch (Larix decidua Mill.) fretwork patterns cut through by CNC routing and laser at different angles with relate to the grain" presented the experimental work for the determination of the influence of the cutting angle with relate to the grain on the surface quality of larch wood (Larix Decidua Mill.) cut through by laser and CNC routing at different feed-speeds. The authors present an interesting topic, methods are well described and results discussed. Minor revisions are needed:

Authors:

We thank the reviewer for the kind appreciation and the suggestions for improvement!

 

1. It is necessary to think about the title of the article. I propose to simplify and not replace the abstract with the title of the article. 

Authors:

The title was shortened: Comparative surface quality of larch (Larix decidua Mill.) fretwork patterns cut through by CNC routing and by laser

1. Line 39 literature cited in this way is not professional. Please describe in more detail.

Authors:

The literature was described in more detail:

„Research on Norway maple, which has a uniform texture, has indicated that roughness parameters (Ra, Rsk, Rt, Rk, Rpk, and Rvk) increased with the laser power and decreased with the laser scanning speed [3]. However, comprehensive studies on surface roughness of wood surfaces cut by the laser are not many and are limited to a few species. The quality of the surface have been also investigated on CO2 laser cut engineered materials, such as MDF [4], melamine faced particleboard and phenolic resin boards [5], measuring Ra roughness parameter [4], Rz roughness parameter [5]. The results showed that the roughness parameters of the cut surfaces decreased with the increasing laser power and focal point position of the laser beam.”

 

1.  The article does not set assumptions (hypotheses) that would better support the scientific contribution.

Authors:

line 250: When the wood reaction against splitting is higher than the strength of material, surface failure occurs and this appears when cutting takes place under an angle different than 0º with relate to the grain.

1. In Figures 17, mark the laser method with a different line type (dashed line).

Authors:

Done!

 

1. The authors present the measured values ​​of the monitored parameters in graphs. The article needs to be supplemented in the discussion and conclusion with the results of the mutual synthesis of measurements. It is necessary to clearly determine which of the changed parameters (angle, sliding speed) has the greatest or least effect on the resulting surface quality. Due to the number of monitored parameters, I recommend using the statistical evaluation method.

 

Authors:

The results of Rk, as best characterizing the processing, were presented in Table 1 with mean values and standard deviations and were analysed with Duncan test for significance of the two variables: cutting angle and feed speed

It was specified (in line 206): „Considering the influence on Rk of the cutting angle and the feed speed, the cutting angle was the most significant parameter after statistical analysis with ANOVA and Duncan multiple range test (p<0.05)”.

 

1. The conclusion should be supplemented by recommendations that ensure the best quality of the treated surface. Describe the pros and cons of CNC versus laser surface treatment.

 

Authors:

Conclusions chapter was supplemented with results  and comments highlighted in red.  The recommendation for the best quality is included: „By far, the best processing roughness was obtained when cutting along the grain, at a feed speed of 2 m/min...”

line 426: „The processing roughness measured by Rk along the grain gave the best surface quality and was similar for both types of processing: CNC and laser, especially when milling took place with a 2 m/min feed speed.

Comparison laser-CNC in discussion chapter, last paragraph: „In conclusion, processing with CNC at 2 m/min gives similar processing roughness as the laser, with the advantage of a surface unchanged in colour and not affected by carbonization. However, if processing under angles different than 0 is required, laser offers a better quality due to the smoothing effect produced by material melting.”

The comparison is also added in Conclusions: „An increase in the cutting angle to 15º has tripled the quality difference between the laser and CNC, in favor of the laser. The surface processed by CNC does not cause carbonization, but laser tends to smooth the surface irregularities by melting wood, especially in latewood areas.

Author Response File: Author Response.docx