System of Investment Casting in China
What is post tension system?
Post-tension is a way of reinforcing concrete or other material
with high-strength steel strands or bars. Its applications
include buildings, parking structures, bridges, rock and soil
anchors, ect. In many cases, post tensioning allows
construction, which would otherwise be impossible due to either
site constraints or architectural requirements. Post-Tensioning
Systems are world renowned for reliability and performance, most
suitable for all applications in post-tensioned construction.
They embrace the entire spectrum from bridge construction and
buildings to civil applications, above and below ground.
Why post tensioning?
Architects, Structural Engineers, General Contractors, Real
Estate Developers, and Owners incorporate post-tensioning
systems on their projects in order to achieve economy,
efficiency, quicker construction and lower lifetime cost of the
structure. Why? Because Post-Tensioning enhances concrete
strength both under compressive and tensile stresses.
How does post tension system work?
Post-tensioning is where prestress is permanently introduced
into the concrete structure after the concrete has hardened. By
stressing properly positioned high strength prestressing
tendons, Post-Tensioning System introduces constructive stress
into the concrete structure, thus increasing overall
productivity and usage efficiency of construction materials.
Post-tensioned systems should only be designed and installed by
specialist companies. Designing the shape of the PT layout and
specifying the right system is a vital stage in the process and
requires sound engineering consideration in order to maximize
the benefits for all the stakeholders in a project. For example,
in the case of ground slabs, design of the post-tensioning
involves the careful analysis of the loads applied to the slab,
the interaction between the slab and the ground that supports
it, restraint forces and temperature effects. The techniques can
be extended to deal with weak ground where the ground acts as
the permanent formwork and the slab bridges between piles and/or
ground beams. This avoids expensive ground improvement work.
Work on applying the post-tensioning system can begin after any
formwork or bottom reinforcement has been installed. Typically,
for a bonded system, ducting will be laid out first, then
strands will be installed with the help of a strand-pushing
machine and end anchorages will be placed. Concrete placement
follows next. When the concrete has attained its minimum
strength, the strands are anchored in a common anchorage device
and stressed with a large, multi-strand jack. When the jack
reaches the correct load, it releases the tendon. The tendon
then retracts slightly, activating the anchoring system and
creating a tight lock on the tendon. The anchor maintains the
applied force in the tendon and transfers it to the surrounding
concrete. The duct is then filled with a cementitious grout that
provides corrosion protection to the strand and bonds the tendon
to the concrete surrounding the duct.
What kinds of investment castings does my foundry make for
post tension system?
*Bonded Flat slad anchors
*Unboned monostrand anchors
My foundry normally makes such castings for post tension system
with investment casting material gray iron 250. Investment
casting process will ensure post tension system parts in net
shape and reduce machining job, which will be helpful for cost
saving. Tooling will first be made before production, as the
quantity for such parts is large, so we suggest metal mould.
Except casting, machining service is also available in our
Will the quality of investment cast post tension parts be
Quality assurance is also very important for our clients, common
quality problems of products are low hardness, internal defects
(gas cavity).When sample is ready, we will cut a small piece
from sample body and test the hardness first to check whether
our product is qualified. Regarding internal gas cavity, we
could test by X-ray.
Key benefits of post tension castings from our foundry:
*We are the end manufacturer, so we could cast out high quality
*The production cost for post tension castings is low. So
correspondingly, the unit price will also not high.
*Our allocative material will be unique, which will ensure long
working life of post tension castings.
*Expect post tension castings, we could also custom other
investment castings for civil applications according to our
customer's drawing or sample, so as to meet various need of
Home Page | More Articles