MTT stocks and supplies a large range of product for all facets of timber needs in underground mine production. The stock holding not only allows us to handle urgent/emergency situations but also provides an ability to offer product which has been “aged” and thereby the effects of shrinkage are somewhat mitigated whilst the elements have gained an increase in strength. Future load testing will generate a new set of reference data for industry to reliably depend upon in this regard.
The key products are :
- CribLoc – MTT enhanced version of the system used for sometime in industry
- RhinoLoc – MTT system which not only makes square cogs but enables tri-cogs to be constructed
- WedgePac – MTT “pre-load” system to provide a specific loading on the roof
- All other miscellaneous timber sizes as required on site including wedges,plates and caps
Enhancements to the system used for some time in the industry have been inevitable. Whilst the system was effective in reducing the weight per element the work force needed to put it up little has been undertaken to improve its performance since it came to the market.
MTT has re-engineered the notching profile to enable a tighter more secure fit. This goes along way towards ensuring a square vertical cog is constructed with minimal overturning of individual elements as the load is applied. It also has a chamfered lead in edge which assists in assembly particular at heights when the installer is virtually working by feel to get the element into position.
In combination with species and grading improvements, the overall cog constructed from MTT CribLoc look superior and are performing accordingly.
MTT has a range of sizes it is currently producing for the industry :
- 1200mm triple notched
This system incorporates a retainer inserted into the ends of profiled timber elements which lock together securely. The geometry enables both a square or triangular cog to be constructed from the same elements.
Contrary to perception of published information at the time and over the years since the advent of 100% contact systems a square cog constructed from 150mm x 75mm elements uses the same wood volume as does an original “4 pointer” constructed from 150mm x 150mm. In NSW the current practice of using 87mm wide elements actually uses more than the original “4 pointers”.
With still a substantial amount of timber in contact the tri-cog version load carrying capacity remains significant whilst 25% less timber is used. Combining this with an “aged” timber product which further enhances the strength of timber whilst mitigating shrinkage issues is a very logical combination for long term applications such as seals.
Other potential benefits are perceived as below :
- In the Longwall Recovery phase the option of being able to construct a square cog or tri-cog from the same elements “on the spot” is considered an exceptional capability in dealing with tough ground control and shield removal conditions. With the apex pointed outbye the area of movement for a chock to be moved adjacent is improved.
- The potential for assistance in ventilation is also perceived with the apex of the triangle directed towards air source.
- From a cost and environmental view point there are potentially significant gains as well not only in the procurement side of things but also transport to site, logistics and transport down the pit as well as installation costs.
Final RhinoLoc load testing data will be available in the second 1/4 of 2019 upon commissioning of the MTT Load frame.
In order to fully take advantage of the capabilities of timber in strata control MTT identified an ability to apply a load to the roof from within the cog is a must.
To this point in time MTT has developed a proto-type product in the form of an installation kit which will not only enable the cog to be installed at a specific “pre-load” to the roof at time of installation but it will be able to re-connect if some localised shrinkage has occurred within a reasonable range.
The product will be undergoing final load tests and demonstrations once the load frame is commissioned early 2019 then will be under-going pit trials.
MTT is particularly excited about the potential global outcomes of this innovation as it will provide a means of developing a specified “pre-loaded” beam in the roof for Geo tech Engineers and as such enhance safety and performance outcomes of the strata.
One of the key differences in how MTT does business relates to inventory management. We have invested in substantial stock holdings of raw material. We currently have stock of the equivalent of 1300 cog packs and whilst this is building it is also aging and allowing us the opportunity to provide products that are beginning to mitigate the issues of shrinkage in applications where it is an issue.
Consequently, you are not getting packs of timber which was a tree with birds in it last week. MTT timber that has been cut for some time which allows it to progressively stabilize more and strengthen as timber does as it dries out.
Clearly with such a stock reserve it also offsets any issues of supply should emergencies arise, or rain events occur, and logs cannot be bought into a mill for processing etc.
Moisture content is important in the overall performance of timber as many other parameters such as strength, shrinkage and durability all have a direct relationship to the moisture content. Under ordinary conditions all wood contains some water. It is found in two different forms; free water or bound water.
As shown in the graph below little happens to the timber whilst the free water which sits in the cells cavities is removed. This happens readily as it approaches the fibre saturation point (typically 25% – 30% MC).
From that point on to the Equilibrium Moisture Content, the bound water which was chemically bonded to the cell wall is removed resulting in the contraction of the cells as well as hardening.
From a compressive strength point of view there is a dramatic increase in this capacity as the graph shows.
MTT is particularly excited about exploring product and performance opportunities taking full advantage of timber properties as it really provides the opportunity to tailor product to relevant applications … whether it be short term as in a longwall take off or long term in a seal function.
Timber can do both but just needs to be smartly processed and it can then be instantly loaded.